Codes after performing oil cooler/egr work
Thread Starter
AudiWorld Junior Member
Joined: Apr 2017
Posts: 13
Likes: 3
Codes after performing oil cooler/egr work
Hi all, I just finished up with replacing the oil cooler & lower plate seals, Bypass Valve and the EGR valve due to the notorious leaking issue on the 2013 Audi Q7 TDI.... Everything is back together and car is running great, not overheating and no leaks but I am getting intermittent error codes depending on the day. (see below) We did drain the entire coolant system and refilled and from what I can tell we don't have air in the system after bleeding from the EGR screw... But maybe there is still some in there? Any thoughts would be helpful and thank you!
The primary error is: (I did go ahead and buy a new sensor that is on its way) I am not sure if this error could pop and then cause the others?
13156 - EGR Temperature Sensor 1
P040B 00 [11101101] - Implausible Signal
But I have also seen these but not often:
4820 - Engine Coolant Temp. Sensor (G62)
P0118 00 [00100000] - Signal too High
15499 - Thermal Management
P125A 00 [01101101] - Implausible Coolant Flow
19406 - Exhaust Gas Recirculation Cooler Bypass Control Circuit
P245B 00 [11101101] - Implausible Signal
The primary error is: (I did go ahead and buy a new sensor that is on its way) I am not sure if this error could pop and then cause the others?
13156 - EGR Temperature Sensor 1
P040B 00 [11101101] - Implausible Signal
But I have also seen these but not often:
4820 - Engine Coolant Temp. Sensor (G62)
P0118 00 [00100000] - Signal too High
15499 - Thermal Management
P125A 00 [01101101] - Implausible Coolant Flow
19406 - Exhaust Gas Recirculation Cooler Bypass Control Circuit
P245B 00 [11101101] - Implausible Signal
AudiWorld Super User
Joined: Jan 2021
Posts: 4,567
Likes: 1,456
From: USA - NM
Probably depends on if any those error/fault codes were present before you did the work in the valley or not.
You didn't mention method used when you refilled the coolant system.
The coolant vacuum-fill procedure specified in TSB exists for a reason on this car, so if you didn't use the vacuum fill method or a similar filling tool//method to ensure no air can enter once you begin to fill the system, then you likely have air trapped within the system still, which can create havoc with sensor feedback...like intermittent signals, etc. Even if you did use an 'air blocker' funnel to refill the system, there is likely to be some air trapped within the heater cores, etc.
The two coolant temp sensors are known to go bad on these cars, but they also have specific symptoms you can verify on the car, as well as looking at the dara from them in live data view. I'd check those two against each other when engine is cold, and their output should be within a few degrees of each other based on location on car. One is located at base of radiator on large output hose from bottom of the radiator...that's the one controls the cooling fans feedback circuit, and symptoms include random cooling fan running at max speed, which you can definitely hear if you outside the car, and possibly inside the car as well.
The other coolant temp sensor mounted in back of engine bay same side is more diff to access; it controls feedback loop to ECU and is what the coolant temp readout on dash gauge is based on. If this sensor bad, then the temp readout is likely to jump around/act jittery, and may jump up into the HOT range, then drop back down, etc.
Air trapped inside the coolant system will cause some crazy stuff to happen, so if these codes were not present prior to valley work, take a cold-engine baseline on coolant level in the reservoir; fill to cover over the top of the yellow indicator. Do NOT open the coolant reservoir when engine is still hot, as it is under pressure still. Drive car to get coolant temps up, turn on heaters (sync system up), to MAX heat and run it like this couple minutes at least (windows down helps in temperate weather). Have a good drive around toggling the HVAC controls from hot to cold, etc., and watch the in-car temp gauge for any erratic behavior from cold start onwards. If you want to go crazy, then you can hook up your scan tool while driving and take real time coolant temp readings (have someone else drive or monitor those live temp readings, or you can log them, etc.) Safety first!
Check the reservoir level again once car has cooled down; likely it will have dropped a fair bit from where you filled it to, and that will verify the underlying issue was air trapped in system.
You didn't mention method used when you refilled the coolant system.
The coolant vacuum-fill procedure specified in TSB exists for a reason on this car, so if you didn't use the vacuum fill method or a similar filling tool//method to ensure no air can enter once you begin to fill the system, then you likely have air trapped within the system still, which can create havoc with sensor feedback...like intermittent signals, etc. Even if you did use an 'air blocker' funnel to refill the system, there is likely to be some air trapped within the heater cores, etc.
The two coolant temp sensors are known to go bad on these cars, but they also have specific symptoms you can verify on the car, as well as looking at the dara from them in live data view. I'd check those two against each other when engine is cold, and their output should be within a few degrees of each other based on location on car. One is located at base of radiator on large output hose from bottom of the radiator...that's the one controls the cooling fans feedback circuit, and symptoms include random cooling fan running at max speed, which you can definitely hear if you outside the car, and possibly inside the car as well.
The other coolant temp sensor mounted in back of engine bay same side is more diff to access; it controls feedback loop to ECU and is what the coolant temp readout on dash gauge is based on. If this sensor bad, then the temp readout is likely to jump around/act jittery, and may jump up into the HOT range, then drop back down, etc.
Air trapped inside the coolant system will cause some crazy stuff to happen, so if these codes were not present prior to valley work, take a cold-engine baseline on coolant level in the reservoir; fill to cover over the top of the yellow indicator. Do NOT open the coolant reservoir when engine is still hot, as it is under pressure still. Drive car to get coolant temps up, turn on heaters (sync system up), to MAX heat and run it like this couple minutes at least (windows down helps in temperate weather). Have a good drive around toggling the HVAC controls from hot to cold, etc., and watch the in-car temp gauge for any erratic behavior from cold start onwards. If you want to go crazy, then you can hook up your scan tool while driving and take real time coolant temp readings (have someone else drive or monitor those live temp readings, or you can log them, etc.) Safety first!
Check the reservoir level again once car has cooled down; likely it will have dropped a fair bit from where you filled it to, and that will verify the underlying issue was air trapped in system.
AudiWorld Senior Member
Joined: Mar 2017
Posts: 1,616
Likes: 517
From: Fairbanks, Alaska
Based on the combination of codes, I strongly suspect that you either didn't get these sensors plugged in completely, or you actually have them plugged into the wrong locations. It is very easy to plug at least four separate connectors into the wrong locations (in terms of them reaching one another), so you need to be very careful to get them in the right spots. And, since NONE of them are the same color on both sides (e.g., orange does not connect to orange, etc.), it makes it even more confusing. I took photos of my engine prior to pulling anything apart, and I found that I used those photos quite a bit when putting everything back together. Even though it was only a week or so removed, it is easy to forget....
Thread Starter
AudiWorld Junior Member
Joined: Apr 2017
Posts: 13
Likes: 3
Probably depends on if any those error/fault codes were present before you did the work in the valley or not.
You didn't mention method used when you refilled the coolant system.
The coolant vacuum-fill procedure specified in TSB exists for a reason on this car, so if you didn't use the vacuum fill method or a similar filling tool//method to ensure no air can enter once you begin to fill the system, then you likely have air trapped within the system still, which can create havoc with sensor feedback...like intermittent signals, etc. Even if you did use an 'air blocker' funnel to refill the system, there is likely to be some air trapped within the heater cores, etc.
The two coolant temp sensors are known to go bad on these cars, but they also have specific symptoms you can verify on the car, as well as looking at the dara from them in live data view. I'd check those two against each other when engine is cold, and their output should be within a few degrees of each other based on location on car. One is located at base of radiator on large output hose from bottom of the radiator...that's the one controls the cooling fans feedback circuit, and symptoms include random cooling fan running at max speed, which you can definitely hear if you outside the car, and possibly inside the car as well.
The other coolant temp sensor mounted in back of engine bay same side is more diff to access; it controls feedback loop to ECU and is what the coolant temp readout on dash gauge is based on. If this sensor bad, then the temp readout is likely to jump around/act jittery, and may jump up into the HOT range, then drop back down, etc.
Air trapped inside the coolant system will cause some crazy stuff to happen, so if these codes were not present prior to valley work, take a cold-engine baseline on coolant level in the reservoir; fill to cover over the top of the yellow indicator. Do NOT open the coolant reservoir when engine is still hot, as it is under pressure still. Drive car to get coolant temps up, turn on heaters (sync system up), to MAX heat and run it like this couple minutes at least (windows down helps in temperate weather). Have a good drive around toggling the HVAC controls from hot to cold, etc., and watch the in-car temp gauge for any erratic behavior from cold start onwards. If you want to go crazy, then you can hook up your scan tool while driving and take real time coolant temp readings (have someone else drive or monitor those live temp readings, or you can log them, etc.) Safety first!
Check the reservoir level again once car has cooled down; likely it will have dropped a fair bit from where you filled it to, and that will verify the underlying issue was air trapped in system.
You didn't mention method used when you refilled the coolant system.
The coolant vacuum-fill procedure specified in TSB exists for a reason on this car, so if you didn't use the vacuum fill method or a similar filling tool//method to ensure no air can enter once you begin to fill the system, then you likely have air trapped within the system still, which can create havoc with sensor feedback...like intermittent signals, etc. Even if you did use an 'air blocker' funnel to refill the system, there is likely to be some air trapped within the heater cores, etc.
The two coolant temp sensors are known to go bad on these cars, but they also have specific symptoms you can verify on the car, as well as looking at the dara from them in live data view. I'd check those two against each other when engine is cold, and their output should be within a few degrees of each other based on location on car. One is located at base of radiator on large output hose from bottom of the radiator...that's the one controls the cooling fans feedback circuit, and symptoms include random cooling fan running at max speed, which you can definitely hear if you outside the car, and possibly inside the car as well.
The other coolant temp sensor mounted in back of engine bay same side is more diff to access; it controls feedback loop to ECU and is what the coolant temp readout on dash gauge is based on. If this sensor bad, then the temp readout is likely to jump around/act jittery, and may jump up into the HOT range, then drop back down, etc.
Air trapped inside the coolant system will cause some crazy stuff to happen, so if these codes were not present prior to valley work, take a cold-engine baseline on coolant level in the reservoir; fill to cover over the top of the yellow indicator. Do NOT open the coolant reservoir when engine is still hot, as it is under pressure still. Drive car to get coolant temps up, turn on heaters (sync system up), to MAX heat and run it like this couple minutes at least (windows down helps in temperate weather). Have a good drive around toggling the HVAC controls from hot to cold, etc., and watch the in-car temp gauge for any erratic behavior from cold start onwards. If you want to go crazy, then you can hook up your scan tool while driving and take real time coolant temp readings (have someone else drive or monitor those live temp readings, or you can log them, etc.) Safety first!
Check the reservoir level again once car has cooled down; likely it will have dropped a fair bit from where you filled it to, and that will verify the underlying issue was air trapped in system.
Thank you for responding, very much appreciated. I did go back and look at a couple old logs and it does show the EGR Temp sensor 1 error (P040B) before the work was performed. So I am hoping this is just a bad sensor. I will try to gather some baseline data before and after the replacement. As far as refilling coolant, I did not have the proper equipment or availability for the vacuum fill, so I used the funnel fill process and then ran the car up to temp with the heat blasting and filled as needed and then check for air in the system at the EGR bleeder valve. Heat works great, the gauge is not erratic and the car is no longer sucking any coolant and not overheating. If I continue to have the error for the temp sensor I will log that as you proposed. Thanks again!
Thread Starter
AudiWorld Junior Member
Joined: Apr 2017
Posts: 13
Likes: 3
Based on the combination of codes, I strongly suspect that you either didn't get these sensors plugged in completely, or you actually have them plugged into the wrong locations. It is very easy to plug at least four separate connectors into the wrong locations (in terms of them reaching one another), so you need to be very careful to get them in the right spots. And, since NONE of them are the same color on both sides (e.g., orange does not connect to orange, etc.), it makes it even more confusing. I took photos of my engine prior to pulling anything apart, and I found that I used those photos quite a bit when putting everything back together. Even though it was only a week or so removed, it is easy to forget....
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