2003 Trailblazer Reduced Engine Power / SES lights

While driving in cold temperatures (5 - 15 degrees), two times the Reduced Engine Power light and Service Engine Soon lights come on and the vehicle chugs and will not go more than 10MPH. This happened in January of this year and the dealer replaced the MAP sensor. Then again today, same thing happened. The dealer just cleaned and reset the sensor today. They also told me to use Shell brand 89 octane fuel. About 1 hour later, the SES light came on again. I called back and they are going to look at it again tomorrow. This is a very scary thing as I drive to work very early in the morning (4 a.m) and there's not much help out at that time in the morninig. Since this exact problem has happened twice, is there anything safety wise GM should do? I also hear a pinging noise coming from under the hood when idleing. I will ask the dealer to check this out if it is related. Any advice would be appreciated. I do see that someone else has had these problems.

While driving in cold temperatures (5 - 15 degrees), two times the Reduced Engine Power light and Service Engine Soon lights come on and the vehicle chugs and will not go more than 10MPH. This happened in January of this year and the dealer replaced the MAP sensor. Then again today, same thing happened. The dealer just cleaned and reset the sensor today. They also told me to use Shell brand 89 octane fuel. About 1 hour later, the SES light came on again. I called back and they are going to look at it again tomorrow. This is a very scary thing as I drive to work very early in the morning (4 a.m) and there's not much help out at that time in the morninig. Since this exact problem has happened twice, is there anything safety wise GM should do? I also hear a pinging noise coming from under the hood when idleing. I will ask the dealer to check this out if it is related. Any advice would be appreciated. I do see that someone else has had these problems.

This is a "fly by wire" system..your throttle is electronically controlled..if the light came on, it stored a code most likley for the APP system..there are a few bulletins (GM TSBs) on that concern.
Also I have found that the electric fan clutch can cause a pinging sound

This is a "fly by wire" system..your throttle is electronically controlled..if the light came on, it stored a code most likley for the APP system..there are a few bulletins (GM TSBs) on that concern.
Also I have found that the electric fan clutch can cause a pinging sound


Thanks, but I have another question. How do I look up these GM TSB's for my Trailblazer? Also, should I worry about the fan clutch issue or just have the dealer check it out next time it's in? Thanks.

Thanks, but I have another question. How do I look up these GM TSB's for my Trailblazer? Also, should I worry about the fan clutch issue or just have the dealer check it out next time it's in? Thanks.

When you bring your vehicle into the dealer, part of the techs job during diagnosis is to check for bulletins that may apply to your concern..these TSBs direct the tech into specific repair procedures for a concern.

I had a situation very similar to this in my 04 trailblazer and the dealer told me they pulled a code P1680. They found an app sensor that had an internal open and replaced the app sensor assembly with an adjustable pedal option (I assume sensor). This was covered under my warranty so I am not sure what it cost but it is very unnerving to feel that you can't really rely on your new car.

Hello everyone,i m from Turkey and i had a 2003 chevy trailblazer.I had a situation like this.Reduced Engine Power Light sometimes came on while driving ,the car didn't stop but i can't pass 2000 rpm and i hear sounds like boom interruptedly while reduced engine power light came on.Sometimes it didn't come on,but when came on once,i rerun but the light came on a few times and the car went to safe mode.I rerun when the light came on for go home .When i rerun the engine the Light go out and i can drive it normally.I changed the spark plugs yesterday because the car knocking and one of the spark plug's nail broken.The exhaust had broken from inside and when the engine is idling ,sounds like 'tick tick tick 'came on from exhaust.We test the car with computer and APP1 sensor faulty.We searched and we find this ''Between The gas pedal and the are in miscommunication.I have questions for you..Can these situations can relevant with catalyzator?Can it clogged?Should I change the gas pedal ? Can the sensor out of work ?The car knocking in first gas.Yesterday,we cleaned the throttle body.Should a space between in it? Because i saw a little space in it. When i accelerate hard,sometimes the car accelerate fast but sometimes slowly.Can you help me ? Thanks for answers.

Hello everyone,i m from Turkey and i had a 2003 chevy trailblazer.I had a situation like this.Reduced Engine Power Light sometimes came on while driving ,the car didn't stop but i can't pass 2000 rpm and i hear sounds like boom interruptedly while reduced engine power light came on.Sometimes it didn't come on,but when came on once,i rerun but the light came on a few times and the car went to safe mode.I rerun when the light came on for go home .When i rerun the engine the Light go out and i can drive it normally.I changed the spark plugs yesterday because the car knocking and one of the spark plug's nail broken.The exhaust had broken from inside and when the engine is idling ,sounds like 'tick tick tick 'came on from exhaust.We test the car with computer and APP1 sensor faulty.We searched and we find this ''Between The gas pedal and the are in miscommunication.I have questions for you..Can these situations can relevant with catalyzator?Can it clogged?Should I change the gas pedal ? Can the sensor out of work ?The car knocking in first gas.Yesterday,we cleaned the throttle body.Should a space between in it? Because i saw a little space in it. When i accelerate hard,sometimes the car accelerate fast but sometimes slowly.Can you help me ? Thanks for answers.
Best to start a New/Thread -Post on your problem.
This thread is very old and was worked by one of the AF members that has passed away.

If service light coming and going off on restart get it on a good engine capable scanner that wil read out past and history and present codes and post back all code no.
Or at least check code no with engine running light on before turning engine off.

To check for clogged exhaust check engine vacun at idle and at 2K rpm.
If less at 2K RPM THAN IDLE YOU HAVE A CLOGGED EXHAUST.

Best to start a New/Thread -Post on your problem.
This thread is very old and was worked by one of the AF members that has passed away.

If service light coming and going off on restart get it on a good engine capable scanner that wil read out past and history and present codes and post back all code no.
Or at least check code no with engine running light on before turning engine off.

To check for clogged exhaust check engine vacun at idle and at 2K rpm.
If less at 2K RPM THAN IDLE YOU HAVE A CLOGGED EXHAUST.




thanks for answering .


i have an another problem.while using cruise ,the tachometer is decreasing while the car on ramp.also speed is decreasing and the engine get drowned.But Reduced Engine power light not came on.I can feel when the light come on while driving .because reduced in power and rpm and the engine get drowned while pressing the gas..on a ramp .I can't remember the code but i know and my dealer said to me ..there is a miscommunication between the throttle body and the gas pedal..The car have LPG.but this situation happen on both of gasoline and the lpg.
Other problem is when braking ,the brake pedal sometimes knocking and has a few vibration.

thanks for answering .


i have an another problem.while using cruise ,the tachometer is decreasing while the car on ramp.also speed is decreasing and the engine get drowned.But Reduced Engine power light not came on.I can feel when the light come on while driving .because reduced in power and rpm and the engine get drowned while pressing the gas..on a ramp .I can't remember the code but i know and my dealer said to me ..there is a miscommunication between the throttle body and the gas pedal..The car have LPG.but this situation happen on both of gasoline and the lpg.
Other problem is when braking ,the brake pedal sometimes knocking and has a few vibration.

Well what did the dealer say to do to fix it?

With a code there is repair flow charts in good repair information for codes.
get the code no and go threw the repair flow chart for the code.

Also the same with the braking problem.
You have a abs problem.
Get the abs code and go from there.

For us to help we need code no engine running code and ABS brake code no.
If you can get code no post back codes.
Also engine idle and eng vacumn reading at @ 2K RPM

Well what did the dealer say to do to fix it?

With a code there is repair flow charts in good repair information for codes.
get the code no and go threw the repair flow chart for the code.

Also the same with the braking problem.
You have a abs problem.
Get the abs code and go from there.

For us to help we need code no engine running code and ABS brake code no.
If you can get code no post back codes.
Also engine idle and eng vacumn reading at @ 2K RPM






thanks..i will do what i should to do,and tell you after that..tomorrow i will talk with my dealer and get codes to
my dealer suggest to change the pas pedal to fix it ..(And he said to me ,gas pedal and sensor combined in one part so we should change them both.) But after that they can't give a guarantee to fix it and they said that ,they can change throttle body if they can't fix it with changing gas pedal.

thanks..i will do what i should to do,and tell you after that..tomorrow i will talk with my dealer and get codes to
my dealer suggest to change the pas pedal to fix it ..(And he said to me ,gas pedal and sensor combined in one part so we should change them both.) But after that they can't give a guarantee to fix it and they said that ,they can change throttle body if they can't fix it with changing gas pedal.

Sounds like your dealer is being honest with you.
If you get code no post them back for more help.
Good Luck