Location of Crankcase Pressure Sensor?

[zombiedude]

Just did intakes on my 3.3T and started getting a P04DB code for disconnected vacuum line. Checked all my connections and they seem good. Retightened everything and the code went from coming up every drive (2-3 miles), to popping up only every 100 or so miles. Trying to troubleshoot with tests over 100 miles isn’t very fun, so hoping I could cut down some areas that could be causing the issue if I could find out where the sensor that throws the code is located. Obviously has something to do with one of my connections, problem is just finding which one. Even under full load @16lbs of boost it doesn’t always throw the code.

Anyone here know? Or know what diagram I could look to find it?

 

[Kodiack]

So that code is for cranckcase ventilation is disconnected...ie: low vacuum detected within intake.
Its probably due to the intakes not being designed to actually provide vacuum for the PCV and crankcase ventilation to work properly.
What intakes did you install?
Maybe someone who also has them can chime in.
You dont seem to be the only one.

https://www.reddit.com/r/GenesisG70/comments/1foqp8f/cel_after_cold_air_intake_install

 

[zombiedude]

So that code is for cranckcase ventilation is disconnected...ie: low vacuum detected within intake.
Its probably due to the intakes not being designed to actually provide vacuum for the PCV and crankcase ventilation to work properly.
What intakes did you install?
Maybe someone who also has them can chime in.
You dont seem to be the only one.

https://www.reddit.com/r/GenesisG70/comments/1foqp8f/cel_after_cold_air_intake_install

I did the BMS intakes, which seem common enough. The few Reddit posts I’ve scrolled through didn’t seem to have any answers beyond swapping to a different system. I feel like there’s got to be something to fix the problem though.

 

[oddball]

There is never a vacuum in the intake tubes - outside the throttle body. There is only a vacuum inside the intake manifold.

This code, based on what y'all said, is saying there isn't enough flow through the PCV valve. Re-check your connections especially around catch cans if you installed any. If you really left a manifold connection un-done then the car would have a very difficult time running at all.

 

[zombiedude]

There is never a vacuum in the intake tubes - outside the throttle body. There is only a vacuum inside the intake manifold.

This code, based on what y'all said, is saying there isn't enough flow through the PCV valve. Re-check your connections especially around catch cans if you installed any. If you really left a manifold connection un-done then the car would have a very difficult time running at all.

I’m not exactly sure what the parameters for triggering the code are, but I can pretty much guarantee it’s something to do with the intakes. Others have received the same code after doing intakes, I hadn’t installed a catch can so that can’t be it. And the code is coming up less often after retightening everything (but any tighter doesn’t seem to be a great solution as it’s already super tight). I did have a buddy suggest some KN air tight intake sealant.. any concerns with giving this a try? I don’t see why not.

Edit- also not saying you’re wrong, just to be clear! I don’t know much when it comes to mechanical engineering and how these systems work. You sound much more knowledgeable than me, just trying to connect the dots and I don’t see how an unrelated part could be the culprit. I did verify and the PCV hose/valve is connected and secured.

 

[Thomby]

I did have a buddy suggest some KN air tight intake sealant.. any concerns with giving this a try? I don’t see why not.

This could potentially help you from pulling unfiltered air through a leak, but it's not likely to resolve any kind of vacuum leak because, like @oddball said, the parts in question are not subject to vacuum.

Engine vacuum is generated when the pistons move down, while the intake valves are open, and the throttle is closed. So it's behind the throttle plate, in the intake manifold. The air filters and intake piping leading to the turbos can't be under vacuum because they're in front of the throttle and open to the atmosphere.

I would check for connections around the intakes you might've messed with during install, and perhaps the PCV system:

Kia Stinger - Emission Control System

Kia Stinger - Positive Crankcase Ventilation (PCV) Valve - Crankcase Emission Control System

 

[zombiedude]

This could potentially help you from pulling unfiltered air through a leak, but it's not likely to resolve any kind of vacuum leak because, like @oddball said, the parts in question are not subject to vacuum.

Engine vacuum is generated when the pistons move down, while the intake valves are open, and the throttle is closed. So it's behind the throttle plate, in the intake manifold. The air filters and intake piping leading to the turbos can't be under vacuum because they're in front of the throttle and open to the atmosphere.

I would check for connections around the intakes you might've messed with during install, and perhaps the PCV system:

Thank you for those links! I’ll take a look around each part to see what I can find. Worst case, is there any diagnostic test to identify the leak if I need to take it to a shop?

The car runs perfectly fine, it holds boost, no rough idle, no stutter on acceleration. Very strange. Only annoying part of the code is the CEL on my dash. Doesn’t put me in limp mode or anything.

 

[oddball]

Unfortunately the kiastinger.com service manual is only for the 4 cylinder. The PCV system is quite different on the v6. It's not all that complicated, just follow the hoses. Fresh air goes in one side of the engine through the driver side valve cover via that hose connected to the driver side intake tube, flows through the engine picking up oil and contaminants, exits the engine through the other side valve cover and into the intake manifold.

The only thing that should've been messed with is the hose that goes from the driver side intake tube back towards the engine. That connected to the stock intake tube and should've been moved to the new BMS tube. Make sure you didn't yank off the other end of that hose or anything. Take a look in the BMS intake and make certain that barb fitting is good - everything is machined properly and the fitting is installed correctly. Dumb shit happens.

I would not use that intake sealant for anything in the world. All the connections are silicone fittings with hose clamps - those seal very easily.

It's worth taking off the engine cover and re-checking every hose connection.

A super quick internet search makes it sound like some cars just throw this code for unknown reasons when aftermarket intakes are installed. Luck of the draw. You'd need to have a high quality code reader that can do OEM ECU control to debug this, as well as the correct service manual debug procedure. Or just clear the code whenever it comes up.

The code will probably fail emissions checks if you're required to pass those, so keep that in mind.

 

[zombiedude]

Unfortunately the kiastinger.com service manual is only for the 4 cylinder. The PCV system is quite different on the v6. It's not all that complicated, just follow the hoses. Fresh air goes in one side of the engine through the driver side valve cover via that hose connected to the driver side intake tube, flows through the engine picking up oil and contaminants, exits the engine through the other side valve cover and into the intake manifold.

The only thing that should've been messed with is the hose that goes from the driver side intake tube back towards the engine. That connected to the stock intake tube and should've been moved to the new BMS tube. Make sure you didn't yank off the other end of that hose or anything. Take a look in the BMS intake and make certain that barb fitting is good - everything is machined properly and the fitting is installed correctly. Dumb shit happens.

I would not use that intake sealant for anything in the world. All the connections are silicone fittings with hose clamps - those seal very easily.

It's worth taking off the engine cover and re-checking every hose connection.

A super quick internet search makes it sound like some cars just throw this code for unknown reasons when aftermarket intakes are installed. Luck of the draw. You'd need to have a high quality code reader that can do OEM ECU control to debug this, as well as the correct service manual debug procedure. Or just clear the code whenever it comes up.

The code will probably fail emissions checks if you're required to pass those, so keep that in mind.

Thanks for writing all this up. It does seem to be luck of the draw. I did pop off the cover and followed the lines, nothing stood out unfortunately. I will say that the BMS intakes were installed and running smoothly for a couple weeks, I then did the silicone inlet tubes which is when the code started to come up. Only thing that would’ve been removed in the process was the hose in the image attached. I did do the recirculating breather hose delete for the BOVs but that was also earlier in time and didn’t cause any issues previously. I have just been clearing the codes which is a pain, but luckily it’s a new vehicle so I won’t have to do emissions testing for 4 years in my state. I’ll probably start swapping in oem parts one at a time to see if I can narrow down the problem child here and see where that takes me. Obviously troubleshooting over the internet isn’t the greatest sometimes so this seems like the most logical next steps. Just hoped to have avoided redoing any work, I did keep the OEM parts though which is good. I appreciate all the help!

 

[BIG-D]

Got a pic of the second pcv hose?
There are two on that side that connect to the intake tube.

 

[zombiedude]

Got a pic of the second pcv hose?
There are two on that side that connect to the intake tube.

I’m gonna try replacing this hose. I had to pull pretty hard to remove it as it was a tight fit. I don’t see any issues with it, but maybe a small tear was made.. out of everything during the install, this was the only thing that gave me trouble, even if it was only for a moment.

 

[SRV]

I did not read all the replies above as I'm short on time, so not sure if the following has been mentioned already:

The error is that there is not enough vacuum in the crankcase.

The crankcase is sealed and it gets its vacuum from the intake, and fresh air from after the MAF (..or whatever is measuring the mass of air).

You could have low vacuum from a leaky valve cover, a grommet, or most likely a disconnected vacuum hose.

 

[Thomby]

I’m gonna try replacing this hose. I had to pull pretty hard to remove it as it was a tight fit. I don’t see any issues with it, but maybe a small tear was made.. out of everything during the install, this was the only thing that gave me trouble, even if it was only for a moment.

If that's the hose that connects to the intake directly behind the filter, the only thing a crack/tear would potentially do is introduce unfiltered air. It would not be a vacuum leak because the end is open to the atmosphere and it's not pulling already metered air (its source is in front of the MAP & TMAP sensors).

The easy way to prove this correct or incorrect would be to unhook the front of that line completely from the intake. I bet it won't make a bit of difference since it's already seeing atmospheric pressure.

Edit: haven't been under the hood in a bit, but I believe the one connecting to the intake tube is for idle air (so plugging it at idle may make the engine falter/die), while the one below and to the left of it (right angle bend, connects just in front of turbo inlet) is the PCV feed line. Is that right @oddball?

 

[zombiedude]

If that's the hose that connects to the intake directly behind the filter, the only thing a crack/tear would potentially do is introduce unfiltered air. It would not be a vacuum leak because the end is open to the atmosphere and it's not pulling already metered air (its source is in front of the MAP & TMAP sensors).

The easy way to prove this correct or incorrect would be to unhook the front of that line completely from the intake. I bet it won't make a bit of difference since it's already seeing atmospheric pressure.

Edit: haven't been under the hood in a bit, but I believe the one connecting to the intake tube is for idle air (so plugging it at idle may make the engine falter/die), while the one below and to the left of it (right angle bend, connects just in front of turbo inlet) is the PCV feed line. Is that right @oddball?

So what you’re saying is effectively disconnecting any of these lines wouldn’t produce the issue I’m seeing?

I’m taking a closer look right now and I just found a smidge of oil (see pictures attached) near the location initially mentioned to check. The car is brand new 3k miles so this is definitely new. Could that be related to the issue? I never touched anything near here, in fact it’s beneath the engine cover which I haven’t removed before starting this thread. But maybe just unlucky timing with the work I did? Would this be a potential reason for the code?

I’ll be working on the car for the next 2 hours from this post so if you’re seeing this soon I can check any connections on the spot. I only have access to a garage every Friday so this is my one chance this week to try a fix and troubleshoot.

 

[zombiedude]

Decided to reinstall the OEM accordion style plastic turbo inlet tube on the driver side only since that’s the most likely to be the problem if it’s intake related. Mileage at 3085, Friday March 7th.

I’ve been getting the code consistently every other day. If I go greater than 3300 mileage or 7 days without it popping up. I’ll swap the silicone inlet tube back on to see if I get the code again immediately. Then we’ll know a) it’s the inlet tube if I get the code again or b) I installed it wrong somehow initially if I don’t get the code again.

If I get the CEL while oem is installed, then it’s back to troubleshooting. Worse case scenario I uninstall the handful of aftermarket parts see if the CEL pulls, and if so, take it to the dealership under warranty since it seems like something is wrong beyond what I worked on.

 

[Thomby]

So what you’re saying is effectively disconnecting any of these lines wouldn’t produce the issue I’m seeing?

I don't know the hose layout at the back of the engine well enough to identify those others in your pictures; I'd have to trace where they connect to figure them out.

But a classic "vacuum leak" would be something like a hose sources vacuum from the intake manifold, to power a closed system like the brake booster. When you disconnect or crack the line, you suddenly have atmospheric air being pulled into the engine without going through the MAP/TMAP/MAF sensor, meaning it's unmetered and makes the car run lean.

A line that is already open to the atmosphere, either because it's feeding air into the crankcase for the PCV, or to the idle air system, isn't a closed source of vacuum, and is already pulling however much atmospheric air as it's going to pull. So a leak in anything that connects to the intake upstream of throttle/MAP, or disconnecting one of those lines entirely, should not change anything.

You said you "hadn't" installed a catch can when you did your intakes, does that mean you have one now? Can you check whether that PCV line is pinched/collapsed (vertical hose on rear left of engine, coming vertically from valve cover to intake)? What other modifications have you done under the hood?

 

[zombiedude]

I don't know the hose layout at the back of the engine well enough to identify those others in your pictures; I'd have to trace where they connect to figure them out.

But a classic "vacuum leak" would be something like a hose sources vacuum from the intake manifold, to power a closed system like the brake booster. When you disconnect or crack the line, you suddenly have atmospheric air being pulled into the engine without going through the MAP/TMAP/MAF sensor, meaning it's unmetered and makes the car run lean.

A line that is already open to the atmosphere, either because it's feeding air into the crankcase for the PCV, or to the idle air system, isn't a closed source of vacuum, and is already pulling however much atmospheric air as it's going to pull. So a leak in anything that connects to the intake upstream of throttle/MAP, or disconnecting one of those lines entirely, should not change anything.

You said you "hadn't" installed a catch can when you did your intakes, does that mean you have one now? Can you check whether that PCV line is pinched/collapsed (vertical hose on rear left of engine, coming vertically from valve cover to intake)? What other modifications have you done under the hood?

That all makes sense.

I’ll have to take a picture tomorrow when I get the chance, but the PCV line (what the catch can would connect to) looks fine to me, and I haven’t installed my catch can yet (zero maintenance CC from BMS), so that hose has otherwise been untouched.

The timeline for the troubleshooting so far:

Feb. 12th - BMS intakes (just upper intake tubes), No issues/CEL

Feb. 20th - Stock BOV breather hose delete, capped off the breather hose inlet tube with plugs. No issues/CEL

Feb. 22nd - Bumper removed > vellossa tech LED big mouth snorkels installed, oem accordion plastic turbo inlet tubes removed/BMS silicone turbo inlet tubes installed. No IMMEDIATE issues/CEL

Feb. 24th 2pm - 1st hit for P04DB code at 2,460 miles. No reduction in power, no strange noises, no cause for concern beyond CEL.

Feb. 26th 1pm - 2nd hit. Didn’t note mileage but within 20 miles.

Feb. 28th - 3rd hit. Didn’t note mileage again within 20 miles. Checked and tightened connections. Installed Tial BOV and flange, removed oem BOVs. Drove 150 miles hard afterwards for a car cruise, no codes.

Mar. 1st - Drove 300ish miles to the coast and back. No codes.

Mar. 2nd - 4th hit. ~2900 miles, immediately after leaving apartment on first hard acceleration. Reset codes and drove for about 100 miles, no additional codes.

Mar. 3rd - Next morning, 5th hit, similar fashion, first hard acceleration after starting. ~3000 miles.

Mar. 6th - Morning, 6th hit, same first accel. ~3060 miles.

Mar. 7th - No code today, ~3085 mileage as of writing this. Swapped driver side silicone turbo inlet for oem accordion style part. Reverified connection and traced all vacuum lines, identified one slightly oiled area near PCV line but unconfirmed if this is related. No other changes.

After writing this out, I’ve come to realize it’s happening almost regularly every other day. Let’s see if it keeps that trend up now that I’ve swapped the inlet tube out. Should be able to provide an update shortly.

Currently waiting to be installed: JB4, spark plugs, and zero maintenance catch can. Trying to avoid introducing more variables while troubleshooting.

Also not that it matters, but I’m on the younger side, just turned 22. So thank you all for the valuable information, this is all new to me and I don’t know where I’d be without the endless helpful threads created by you guys! And thanks for helping me troubleshoot this issue especially.

 

[Thomby]

Feb. 20th - Stock BOV breather hose delete, capped off the breather hose inlet tube with plugs. No issues/CEL

Feb. 22nd - Bumper removed > vellossa tech LED big mouth snorkels installed, oem accordion plastic turbo inlet tubes removed/BMS silicone turbo inlet tubes installed. No IMMEDIATE issues/CEL

Feb. 24th 2pm - 1st hit for P04DB code at 2,460 miles.

I don't know the full recirc valve setup from memory, but since you worked on that right before the code popped up, maybe worth looking at. As for the driver's side intake, I don't see how that connection (or the one near it) would cause this problem, unless I'm missing something.

Here's that quad hose (blue) which is the "vacuum intensifier" assembly. It connects to the intake piping in front, the intake manifold at rear left, the brake booster at rear right, and the vacuum pump at bottom rear, with that double valve junction to switch between intake manifold and vacuum pump for the brake booster (when the manifold is under boost). The intake connection is likely just for purging pressure and since it's open to the atmosphere a leak shouldn't do anything.

The red hose connects just past the intake hose on the coupling you replaced (I think). I believe this is just the PCV source, and again since it's effectively open to the atmosphere (only connecting there to pull from behind the filter), I don't see how a leak would introduce additional unmetered air. Now if it's kinked or collapsed, I could see that causing problems, so maybe check along its length.

 

[zombiedude]

I don't know the full recirc valve setup from memory, but since you worked on that right before the code popped up, maybe worth looking at. As for the driver's side intake, I don't see how that connection (or the one near it) would cause this problem, unless I'm missing something.

Here's that quad hose (blue) which is the "vacuum intensifier" assembly. It connects to the intake piping in front, the intake manifold at rear left, the brake booster at rear right, and the vacuum pump at bottom rear, with that double valve junction to switch between intake manifold and vacuum pump for the brake booster (when the manifold is under boost). The intake connection is likely just for purging pressure and since it's open to the atmosphere a leak shouldn't do anything.

The red hose connects just past the intake hose on the coupling you replaced (I think). I believe this is just the PCV source, and again since it's effectively open to the atmosphere (only connecting there to pull from behind the filter), I don't see how a leak would introduce additional unmetered air. Now if it's kinked or collapsed, I could see that causing problems, so maybe check along its length.

View attachment 90042 View attachment 90044

Thanks for the diagrams. Cross referencing this with my findings leads me to point out the oil I found yesterday as it aligns with the image you sent. See red circle. Every (“blue”) hose in that diagram has been triple checked for kinks and disconnections including the (“red”) hose you showed. I did test completely disconnecting the (“red”) hose to atmosphere and wasn’t able to get the code to pop up with a few revs in the garage and a minute idle, not gonna test it while driving but you should be correct in that it isn’t the issue.

At this point are there any sensors or electrical components that meter the air? Maybe one of those are disconnected? But I guess to that extent the issues would be a lot more intense and consistent. God cars can be so troublesome for the littlest things..

 

[zombiedude]

That all makes sense.

I’ll have to take a picture tomorrow when I get the chance, but the PCV line (what the catch can would connect to) looks fine to me, and I haven’t installed my catch can yet (zero maintenance CC from BMS), so that hose has otherwise been untouched.

The timeline for the troubleshooting so far:

Feb. 12th - BMS intakes (just upper intake tubes), No issues/CEL

Feb. 20th - Stock BOV breather hose delete, capped off the breather hose inlet tube with plugs. No issues/CEL

Feb. 22nd - Bumper removed > vellossa tech LED big mouth snorkels installed, oem accordion plastic turbo inlet tubes removed/BMS silicone turbo inlet tubes installed. No IMMEDIATE issues/CEL

Feb. 24th 2pm - 1st hit for P04DB code at 2,460 miles. No reduction in power, no strange noises, no cause for concern beyond CEL.

Feb. 26th 1pm - 2nd hit. Didn’t note mileage but within 20 miles.

Feb. 28th - 3rd hit. Didn’t note mileage again within 20 miles. Checked and tightened connections. Installed Tial BOV and flange, removed oem BOVs. Drove 150 miles hard afterwards for a car cruise, no codes.

Mar. 1st - Drove 300ish miles to the coast and back. No codes.

Mar. 2nd - 4th hit. ~2900 miles, immediately after leaving apartment on first hard acceleration. Reset codes and drove for about 100 miles, no additional codes.

Mar. 3rd - Next morning, 5th hit, similar fashion, first hard acceleration after starting. ~3000 miles.

Mar. 6th - Morning, 6th hit, same first accel. ~3060 miles.

Mar. 7th - No code today, ~3085 mileage as of writing this. Swapped driver side silicone turbo inlet for oem accordion style part. Reverified connection and traced all vacuum lines, identified one slightly oiled area near PCV line but unconfirmed if this is related. No other changes.

After writing this out, I’ve come to realize it’s happening almost regularly every other day. Let’s see if it keeps that trend up now that I’ve swapped the inlet tube out. Should be able to provide an update shortly.

Currently waiting to be installed: JB4, spark plugs, and zero maintenance catch can. Trying to avoid introducing more variables while troubleshooting.

Also not that it matters, but I’m on the younger side, just turned 22. So thank you all for the valuable information, this is all new to me and I don’t know where I’d be without the endless helpful threads created by you guys! And thanks for helping me troubleshoot this issue especially.

Update:

Mar. 8th - Drove 70 miles through 3 separate trips (car was off for more than 3 hours between trips), hard driving multiple pulls from stop lights and from a roll. No hit for the code.

Mar. 9th - kinda expected to get the code based on the every other day basis, but to my delight, so far nothing. Cold started, idled for a few minutes. Medium acceleration out of the neighborhood which had tripped the code twice prior under the same conditions. Once it was warmed up, did a hard pull from a stop light and a few small pulls around town for another 10 miles. No codes, no issues. At about 3,165 miles.

Last hit was on the 6th @ 3,060 miles. Been 3 days and 100 miles which is beyond the typical threshold. If I continue to not get the code, 5 more days or 140 miles and I’ll swap back to the silicone tube to see if it replicates the issue.