CEL and P2237 code
12-30-2013, 03:02 PM
#1
Drifting
Thread Starter
CEL and P2237 code
Had the CEL light up and stay on, so checked the codes with a durametric. Came up with
P2237 - Lamda control adaptation at idle Bank 2. No signal communications. Test conditions not completed. Fault currently active and causing DTC light.
Anyone know what that means? I have cleared it at this point, but have not gone for a drive yet.
P2237 - Lamda control adaptation at idle Bank 2. No signal communications. Test conditions not completed. Fault currently active and causing DTC light.
Anyone know what that means? I have cleared it at this point, but have not gone for a drive yet.
12-31-2013, 03:35 PM
#2
I don't know what part is likely to be causing this issue, but perhaps I can shed some light on the message.
First, Bank 2 just refers to one side of the engine--they are referred to as Bank 1 and Bank 2. I'm not sure how the Cayenne engine is named for these purposes.
When you cold start your vehicle, the ECU makes the engine run rich for a minute or so to help warm up the cats. Lambda refers to the ratio of oxygen to fuel that is measured by the O2 sensor in front of the cats. The ECU uses the signal from that O2 sensor (aka Lambda sensor) to adjust the air-to-fuel ratio entering the cylinders.
Also, the ECU performs self tests of various sensors and systems, and some of those tests occur when the vehicle is at idle.
Looking at your message in light of this, I would guess that the ECU is attempting to test the system by which it controls the air-to-fuel ratio on one side of the engine, and it is not receiving a signal from one of the sensors. It could be the pre-cat O2 sensor, or presumably it could also be a number of other things involved in the process of regulating the air-to-fuel mixture--a sensor at the fuel injector(s), a sensor in the intake air, an exhaust temp sensor, etc.
A quick web search turns up the generic OBDII P2237 code as "O2 Sensor Positive Current Control Circuit/Open." Based on this, I would guess either your pre-cat O2 sensor on Bank 2 is bad, or your connection to that sensor is bad. There should be a place where the sensor wire plugs into a harness. I would check that connection first for tightness and corrosion.
First, Bank 2 just refers to one side of the engine--they are referred to as Bank 1 and Bank 2. I'm not sure how the Cayenne engine is named for these purposes.
When you cold start your vehicle, the ECU makes the engine run rich for a minute or so to help warm up the cats. Lambda refers to the ratio of oxygen to fuel that is measured by the O2 sensor in front of the cats. The ECU uses the signal from that O2 sensor (aka Lambda sensor) to adjust the air-to-fuel ratio entering the cylinders.
Also, the ECU performs self tests of various sensors and systems, and some of those tests occur when the vehicle is at idle.
Looking at your message in light of this, I would guess that the ECU is attempting to test the system by which it controls the air-to-fuel ratio on one side of the engine, and it is not receiving a signal from one of the sensors. It could be the pre-cat O2 sensor, or presumably it could also be a number of other things involved in the process of regulating the air-to-fuel mixture--a sensor at the fuel injector(s), a sensor in the intake air, an exhaust temp sensor, etc.
A quick web search turns up the generic OBDII P2237 code as "O2 Sensor Positive Current Control Circuit/Open." Based on this, I would guess either your pre-cat O2 sensor on Bank 2 is bad, or your connection to that sensor is bad. There should be a place where the sensor wire plugs into a harness. I would check that connection first for tightness and corrosion.
12-31-2013, 04:12 PM
#3
Drifting
Thread Starter
Thanks for the lead. I reset the codes and made sure the fuel cap was tight and I have not had the CEL light return. We will see. It did happen after the car sat at the airport for six days in pretty cold weather. Will keep an eye on it.
01-18-2014, 03:45 PM
#4
Drifting
Thread Starter
Update: ran 500 miles with no CEL. It returned:
P2237:
Lambda control adaptation at idle, Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is currently active and is not causing a DTC light
P2237:
Lambda control adaptation at idle, Bank 2 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
P2235:
Lambda control adaptation at idle, Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2235:
Lambda control adaptation at idle, Bank 1 - No signal/communication, test conditions are not-completed, fault is currently active and is not causing a DTC light
I will have to check the O2 sensor connections. May be a bit as it is winter here and I can't get it anywhere warm for a while. I cleared the faults again. See how long it goes this time.
P2237:
Lambda control adaptation at idle, Bank 2 - Upper limit value exceeded, test conditions are not-completed, fault is currently active and is not causing a DTC light
P2237:
Lambda control adaptation at idle, Bank 2 - No signal/communication, test conditions are not-completed, fault is currently active and causing a DTC light
P2235:
Lambda control adaptation at idle, Bank 1 - Upper limit value exceeded, test conditions are not-completed, fault is not currently active and is not causing a DTC light
P2235:
Lambda control adaptation at idle, Bank 1 - No signal/communication, test conditions are not-completed, fault is currently active and is not causing a DTC light
I will have to check the O2 sensor connections. May be a bit as it is winter here and I can't get it anywhere warm for a while. I cleared the faults again. See how long it goes this time.
07-10-2015, 10:13 AM
#6
Three Wheelin'
The upper limit it's referring to is the long term fuel trim. Your car is no longer able to keep the AFR at stoic.
This happens for 1 of 2 reasons.
Your oxygen sensor is old and needs replacing. As the sensor ages, it starts to read leaner than it actually is, and will subsequently enriched the mixture. It's designed that way so that it doesn't lean out the motor. Your car can only adjust this mixture so far, so once you max out the LTFT, the code is thrown.
The other way is that you have a mechanical problem that is forcing the AFR in a direction not intended by the car. MAF, boost leak, or a bad injector. A bad injector would likely cause a misfire before the trim data gets pegged, though.
The fact you're getting a no communication code, as well, makes me think your oxygen sensors are dead. This is probably going to be a much more common issue as these cars hit that age and mileage where they typically fail - 10 years 100k miles.
They're a Bosch sensor. So need to pay the Porsche tax on this part as the Bosch setup from ECS is the exact same as the Porsche sensor. You can also buy the sensor itself and splice it into your harness. Usually, the sensor itself is only 50 bucks. But, there is something to be said for having a new harness. Replace them in pairs to make sure each bank has the same fuel trim.
This happens for 1 of 2 reasons.
Your oxygen sensor is old and needs replacing. As the sensor ages, it starts to read leaner than it actually is, and will subsequently enriched the mixture. It's designed that way so that it doesn't lean out the motor. Your car can only adjust this mixture so far, so once you max out the LTFT, the code is thrown.
The other way is that you have a mechanical problem that is forcing the AFR in a direction not intended by the car. MAF, boost leak, or a bad injector. A bad injector would likely cause a misfire before the trim data gets pegged, though.
The fact you're getting a no communication code, as well, makes me think your oxygen sensors are dead. This is probably going to be a much more common issue as these cars hit that age and mileage where they typically fail - 10 years 100k miles.
They're a Bosch sensor. So need to pay the Porsche tax on this part as the Bosch setup from ECS is the exact same as the Porsche sensor. You can also buy the sensor itself and splice it into your harness. Usually, the sensor itself is only 50 bucks. But, there is something to be said for having a new harness. Replace them in pairs to make sure each bank has the same fuel trim.
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07-10-2015, 04:50 PM
#8
P2235, P2237 - My Experience
Started getting P2235 randomly. After clearing, it would stay off for ~6 weeks and come back. Clear and then ~4 weeks. Then started getting P2237 (other bank) and it would come back after 1-2 days, finally with additional code of P0441 (Incorrect purge flow).
Research showed that these codes frequently accompanied each other. Didn't notice any performance issues other than occasional cold start roughness that, like above, in relevance to the 2235 & 7 code descriptions, I assumed was failing sensors. Didn't seem right that they would die at relatively the same time though without an underlying cause.
In looking at others experience with P0441, most times it was caused by a failing Evap purge valve. This thread https://rennlist.com/forums/porsche-...tion-pump.html details a similar issue, although the OP never responded if this was ultimately the same fix.
I ended up replacing the Evap purge valve, and have had none of these codes come back in over a month so far. The car also runs noticeably better on cold starts and at idle in general. This thread on pelican gives a good description of the cause and fix with part#'s and good DIY tips. http://forums.pelicanparts.com/porsc...ault-code.html
HTH
Research showed that these codes frequently accompanied each other. Didn't notice any performance issues other than occasional cold start roughness that, like above, in relevance to the 2235 & 7 code descriptions, I assumed was failing sensors. Didn't seem right that they would die at relatively the same time though without an underlying cause.
In looking at others experience with P0441, most times it was caused by a failing Evap purge valve. This thread https://rennlist.com/forums/porsche-...tion-pump.html details a similar issue, although the OP never responded if this was ultimately the same fix.
I ended up replacing the Evap purge valve, and have had none of these codes come back in over a month so far. The car also runs noticeably better on cold starts and at idle in general. This thread on pelican gives a good description of the cause and fix with part#'s and good DIY tips. http://forums.pelicanparts.com/porsc...ault-code.html
HTH
07-13-2015, 06:27 PM
#12
Nordschleife Master
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Mine did the same thing (04 CTT), plus I would sometimes get some oil smoke at startup. Fixed the membrane in the PCV valve and all went away.
Note this usually is due to un-metered air coming into the system. The system shows up as lean and the computer tries to account for it by richening it up. It only has a small window to work with. Then it sets the CEL if it cannot do it anymore.
Note this usually is due to un-metered air coming into the system. The system shows up as lean and the computer tries to account for it by richening it up. It only has a small window to work with. Then it sets the CEL if it cannot do it anymore.
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