Question about 2008 Chevrolet Impala

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'Engine power reduced' comes up along with check engine light. Replaced throttle body the other day but it happen again! Anyone know what is going on and what could be causing this?

I have been reading online about this problem but nobody has had a resolution to this problem. I've read for other people the car slows down and will not go over 20mph. The car doesn't do this for me. It still continues to go the speed I need it to though I don't go over 45mph and turn off the radio, heat, and dim the lights to conserve power. It does hard shift around 2nd gear though. Not every time but often enough to where it's noticeable. I just got it taken in and 'fixed' yesterday. (They replaced the throttle. As well as purge valve and vent valve but that was part of a different problem.) Didn't notice a change in drive but the car shifted hard after driving for 10 min and engine power reduced came on and check engine light is back on. I pulled over and turned off the car. After turning it back on engine power reduced was off but check engine is on yet again. Throws code p1238. I don't want to spend more money blind guessing what it could be as this has already cost 750 bucks! Answers would be VERY greatly appreciated!

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  • Becky Dycz
    Becky Dycz Nov 07, 2014

    Correction I typed wrong! It throws a p2138 code.

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  • Chevrolet Master
  • 40,672 Answers

Check engine lights notify problems in 2 areas . firstly the engine and also the transmission.As you state a problem in the transmission it is possible that is the area of concern. A service dealer will be able to tell you exactly what the sensor fault is for that code.

Posted on Nov 07, 2014

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Posted on Jan 02, 2017

  • 3 Answers

SOURCE: stalling, 'reduced power' light, and OBD code P1125 Manufacturer control air metering...

These trucks have a drive by wire system,we seen a` lot with a broken ground wire on the rear of the drverside cyl head,this is hard to see just feel and give the wire a tug .If the wire is loose or broken the reduced engine power light will come on.

Posted on Feb 15, 2009

  • 6982 Answers

SOURCE: Engine misfire, EGR replaced still rough idle!

First, check the passageway to the egr valve to make sure it is clear (often plugs up with carbon) second, make sure that the egr control is working. Also a good idea to have any codes checked and old ones cleared.Computer may need to cycle a few times to "learn"new parameters.
In general, it is good to shut down your engine when check engine light comes on...The next step after that is to determine why the light came on.
If the cause is an oil related or coolant related item, you should drive no further 'till it's corrected...However, there are numerous sensors that can turn it on with no disasterous results if you continue to drive One example is the light coming on because a gas cap has not been put on correctly...On many vehicles this will turn on the light and set a code, but the car will suffer no damage if you drove to your destination before correcting it.So, if the light comes on and it is not overheating and you have good oil pressure, and you hear no noises from engine, have it looked at but don't put yourself in danger on the side of a major highway for a nonsense code.
Most major parts houses will read codes free...take advantage of that service and get yourself a basic repair manual, so you have an idea what all the stuff under your hood is and does.
Good luck with your car!!

Posted on Apr 26, 2009

  • 462 Answers

SOURCE: engine power reduced

Locate the IP to body harness connector, which may be located in and around the left hand kick panel area or inside the IP. Check to see if there is a water leak into the area and repair as necessary.

Posted on May 24, 2009

  • 2 Answers

SOURCE: Hard Shifting after highway driving (1996 Chevrolet Tahoe)?

converter clutch regulator valve is worn causing line pressure to rise to maximum in turn causing your harsh shifts. Sonax makes a repair kit for it or you can install a stiffer spring to make it work correctly

Posted on May 31, 2009

greg_margo
  • 1959 Answers

SOURCE: Similar Problem: Van bogs down when you step on the gas

2 simple causes for your symptoms would be water in the fuel tank (pour drygas into the tank to alleviate this problem) or a leak in the exhaust system. If both items don't apply, check for any vacuum leaks under the hood. You've isolated the problem to either vacuum leaks or a fuel problem. Hopefully, this will give you a general area to look and solve your problem. Best of luck.
Greg

Posted on Jun 22, 2009

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Reduce power light on has no throttle and keeps giving throttle accuator cdes


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What causes the "Reduced Engine Power", "Service Stability Control" and "Traction Control" warning lights to come on?


the "Reduced Engine Power", problem causes the PCM to disable "Service Stability Control" and "Traction Control" turning on the warning lights to come on for those systems . The reduced engine power is because of a problem with the electronic throttle control system or as GM calls it TAC system . Reduced Engine Power Mode
When the PCM detects a condition with the TAC system, the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
• Acceleration limiting--The PCM will continue to use the accelerator pedal for throttle control, however, the vehicle acceleration is limited.
• Limited throttle mode--The PCM will continue to use the accelerator pedal for throttle control, however, the maximum throttle opening is limited.
• Throttle default mode--The PCM will turn OFF the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The PCM will perform the following actions:
- Limit engine speed to idle by positioning the TP, or by controlling the fuel and spark if the throttle is turned OFF.
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© 2017 General Motors Corporation. All rights reserved.



Drive by Wire training Your best bet , take it to a GM dealer

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1 Answer

Reduced engine power


Have the vehicle checked for DTC'S - diagnostic trouble codes ! Do you know what electronic throttle control is ? The gas pedal assembly has electrical connector an sensors inside ,hooked to the PCM / ECM - engine computer . The engine computer uses these position sensors inputs to control the DC motor on the throttle body to open the throttle plate to control the speed . Plus there are position sensors inside the throttle body to input PCM/ECM to see if it's calculations are corect . Your best bet maybe to take it to a qualified repair shop .
Drive by Wire Function and diagnostics by Wells

Reduced Engine Power Mode
When the PCM detects a condition with the TAC system, the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
• Acceleration limiting--The control module will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
• Limited throttle mode--The control module will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
• Throttle default mode--The control module will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The control module will perform the following actions:
- Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned off.
- Ignore accelerator pedal input.
• Engine shutdown mode--The control module will disable fuel and de-energize the throttle actuator.

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