Code P1515, Reduced Engine Power

JAREDHAXTON

MEMBER
2002 CADILLAC ESCALADE
6.0L
V8
4WD
AUTOMATIC
114,000 MILES

We started receiving Reduced Engine Power light and the car would sputter out but still enable us to drive it home slowly. I started off getting 2 codes. P1221 and P1515. I started simple with replacing the Throttle Position Sensor and had the Throttle Body cleaned. That cleared the P1221 code. But Reduced Engine Power problem would still arise consistently along with the P1515 code.

After continued problems, I had the Mass Airflow Sensor and Throttle Body gasket replaced. We still have the same problem but it is only when it is below freezing outside. Once the weather warms up that day or we start and restart it multiple times, it will operate fine and the code goes away.

It can operate weeks on end so long as we keep it in the garage and wait until it is above 32 degrees or so outside to drive it around. Took it on a trip to California where the low was maybe 45 degrees and it had zero issues.

Any ideas on why it would throw the P1515 code and go into Reduced Engine Power mode only in cold weather and be completely fine otherwise? Thank you!

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,645 POSTS

The code indicates the PCM detects that the commanded and actual throttle positions are not within a calibrated range of each other. Now, you replaced the throttle position sensor and since it seems to only happen below freezing, I would start with the following:

1) Inspect for mechanical concerns or binding that may be temperature related. Components may not move freely in extreme heat or cold due to the presence of contaminants or ice formation.

2) Inspect the TAC module connectors for signs of water intrusion.

If that all checks good, I attached two pics below which are a diagnostic flow chart for this specific code. Take a look through them and let me know if it is something you feel comfortable doing. I have to tell you, there are two throttle position sensors. For some reason, the two aren't in sync with each other. I do have to add that when both of the codes you indicated above are present at the same time, the repair flow chart sends me to first fix the 1221 code. But, since that code is no longer present, I'm providing the steps for the 1515.

I know this sounds confusing. Please feel free to let me know if you have questions or need help. Since it is temperature related, I suspect it is something simple as indicated in the above two things I asked to check.

Take care and let me know if I can help.

Joe

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Saturday, January 18th, 2020 AT 10:31 PM

JAREDHAXTON

MEMBER
7 POSTS

Just to update everyone, I hobbled the vehicle along through a few winters and finally decided to pay whatever money it took (within reason) to fix it in lieu of buying a new or newer vehicle. The problem was the throttle body itself. GM no longer made the part and there appeared to be maybe 1 remanufactured unit in all of the US. Lots of sites pretended to have it but once I paid for it, they would report back that it was not in stock.

O'reilly had one and I had to pay extra shipping on top of the $439.00 to get it. My mechanic swapped it out and it hasn't had the problem since. I fear cold temperatures no more!

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Saturday, January 15th, 2022 AT 9:17 PM

JACOBANDNICKOLAS

MECHANIC
109,645 POSTS

Hi,

Thank you for the update. It's appreciated and will likely help others. Also, I'm glad to hear you got it fixed.

Please feel free to come back anytime in the future. You are always welcome here.

Take good care of yourself,

Joe

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Saturday, January 15th, 2022 AT 9:48 PM