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2023 w/Z51
Driver side inlet fan came on when I shut the car off, even though the water temp was only about 180 and oil temp was 170.
About a week later fan comes on while sitting in a parking lot, engine running. Water temp was 170 and oil temp was 155.
A few days later car had sat over night, pulled it out of the garage and started it. Check engine light came on. Pulled the code: P14D7. Searched and could not find anything on this code. Called OnStar and they provided the following:
ECM - Engine System - P14D7 - The Engine and Transmission System is not performing as expected. An issue has been detected in the Engine Cooling System which monitors and controls engine temperature to maintain optimal operating temperatures and avoid overheating conditions. If you are driving under normal operating conditions, please check the temperature gauge on the instrument panel. If the needle is in the red warning area, the engine is too hot. Pull off the road, stop the vehicle, and turn off the engine as soon as possible. Service within 7 days.
Dropped it off at the dealership. They couldn't figure it out and tried to gently ask if I had been beating on the car. I explained the temps were low on the car and I hand't even driven it when the check engine came on. Did some research on here and there are some similar issues that sound like it could be an ambient air temp sensor in the engine compartment or someone also had an issue with the air inlet temperature sensor. The dealer got back to me and said it's a bad fan which they are replacing. I'm sure there are some scenarios where it could be a fan issue, but honestly it sounds more like a sensor issue to me. When I pointed this out to them they stated there is a temp sensor in a the fan and that was causing the issue. I have not inspected the fan, so this could be the case...but I'm suspicious. Have a feeling I'll be taking it back to the dealer with the same issue in the not too distant future.
Does indeed sound more like a sensor issue than an actual overheating issue. But which of the excessive number of sensors may be hard to determine. The C8 seems to have so many sensors it's not a question of if one will fail, but when.
2023 w/Z51
Driver side inlet fan came on when I shut the car off, even though the water temp was only about 180 and oil temp was 170.
About a week later fan comes on while sitting in a parking lot, engine running. Water temp was 170 and oil temp was 155.
A few days later car had sat over night, pulled it out of the garage and started it. Check engine light came on. Pulled the code: P14D7. Searched and could not find anything on this code. Called OnStar and they provided the following:
ECM - Engine System - P14D7 - The Engine and Transmission System is not performing as expected. An issue has been detected in the Engine Cooling System which monitors and controls engine temperature to maintain optimal operating temperatures and avoid overheating conditions. If you are driving under normal operating conditions, please check the temperature gauge on the instrument panel. If the needle is in the red warning area, the engine is too hot. Pull off the road, stop the vehicle, and turn off the engine as soon as possible. Service within 7 days.
Dropped it off at the dealership. They couldn't figure it out and tried to gently ask if I had been beating on the car. I explained the temps were low on the car and I hand't even driven it when the check engine came on. Did some research on here and there are some similar issues that sound like it could be an ambient air temp sensor in the engine compartment or someone also had an issue with the air inlet temperature sensor. The dealer got back to me and said it's a bad fan which they are replacing. I'm sure there are some scenarios where it could be a fan issue, but honestly it sounds more like a sensor issue to me. When I pointed this out to them they stated there is a temp sensor in a the fan and that was causing the issue. I have not inspected the fan, so this could be the case...but I'm suspicious. Have a feeling I'll be taking it back to the dealer with the same issue in the not too distant future.
Ok. I'm using a 2020 version of the C8 Service Manual obtained from ebay. I can't find a reference to that code. But the description of the Engine Compartment Cooling Fan says it is controlled by an under-hood temperature sensor. It does not say it is integrated with the fan unit, and in fact there is a diagnostic procedure that calls for replacement of the Underhood Air Temperature Sensor. Unfortunately, I could not find the actual replacement procedure for B298 Underhood Air Temperature Sensor. What I did find was a statement that seems to imply that the B298 Underhood Air Temperature Sensor is the same as the Ambient Air Temperature Gauge Sensor Replacement. It may be a mistake, because this seems to be the sensor for the ambient air temperature gauge, and its not deep in the engine compartment, but it is the only one I could find. So, attached is the relevant information. It may be an error. You might ask the dealer why they think the temperature sensor is integrated with the fan. Perhaps someone with a later version of the official manual can look this up.
Ok. I'm using a 2020 version of the C8 Service Manual obtained from ebay. I can't find a reference to that code. But the description of the Engine Compartment Cooling Fan says it is controlled by an under-hood temperature sensor. It does not say it is integrated with the fan unit, and in fact there is a diagnostic procedure that calls for replacement of the Underhood Air Temperature Sensor. Unfortunately, I could not find the actual replacement procedure for B298 Underhood Air Temperature Sensor. What I did find was a statement that seems to imply that the B298 Underhood Air Temperature Sensor is the same as the Ambient Air Temperature Gauge Sensor Replacement. It may be a mistake, because this seems to be the sensor for the ambient air temperature gauge, and its not deep in the engine compartment, but it is the only one I could find. So, attached is the relevant information. It may be an error. You might ask the dealer why they think the temperature sensor is integrated with the fan. Perhaps someone with a later version of the official manual can look this up.
Appreciate you looking it up! I have a strong feeling one of these sensors is the actual issue. The sensor isn't that expensive either, so if it's not fixed I could just do it myself.
Appreciate you looking it up! I have a strong feeling one of these sensors is the actual issue. The sensor isn't that expensive either, so if it's not fixed I could just do it myself.
If it is this one, and I am not certain as I stated, then here it is. It is listed as hiving multiple uses - so it might be.
I’m still a newbie here, Every day I am in awe of the knowledge and expertise of the group. Tho my ‘22 has been problem free (11,600 miles),I am grateful for what you guys share! So a sincere “Thanks!” From the rest of us!!
Update: Got the car back from the dealership. I may have been too quick to complain if the diagnosis they put on the receipt is accurate:
Verified scan for code P14D7 stored found auxiliary left side cooling fan under speed. Found voltage fluctuating between 3.5 volts and 12 volts at terminal 4 and ground.
Correction: Auxiliary Engine Coolant Fan Replacement - Left Side
Haven't driven the car as the weather has been terrible (trailered it to and from the dealership). So no idea if the issue is fixed, will update if anything else happens.
Attached is the schematic for the engine compartment cooling fans. It does not show any sort temperature sensor integrated with the fan units. Instead, it show two separate fan units that are controlled by Fuel Pump Power Control Module. The little symbols (square wave looking symbol) indicates the control is via pulsewidth modulation. That is how it regulates fan speed. You can also see it gets engine compartment temperature data from a single engine compartment temperature sensor. That sensor, I think, is what I mentioned in posts 6 and 8. Now, this doesn't show everything. The Fuel Pump Power Control Module is in communication with the rest of the car systems via the internal network, and we know as fact from another thread that these fans can run continuously if the engine coolant temperature sensor in the engine block fails. So, I'm not saying that engine compartment temperature sensor is the only thing that affects fan action - I'm just saying there is no evidence of a sensor integrated with the fan motors.
Code P14D7
