Reduced engine power light?

Tiny
AMYANDBEN
  • MEMBER
  • 2004 CHEVROLET TRAILBLAZER
  • V8
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
I have the vehicle listed above LT model and my reduced engine power light keeps kicking on while I'm driving where it won't let me drive above 10 MPH. I have to stop the truck and turn it off for a minute then turn it back on and it's fine for maybe a few miles then does it again. What would cause this?
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Tuesday, March 29th, 2016 AT 5:35 AM

13 Replies

Tiny
DL AUTOSHOP
  • MEMBER
Hello, I'm Danny.

Having the check engine light on means there is a diagnostic code or codes stored in your vehicles computer. Is the check engine light on or flashing? You might have engine or transmission codes stored in you trucks computer. The reason why you are feeling loss of power is once your car senses diagnostic codes the vehicle computer will put your car into 'limp mode' to prevent engine damage until the car is fixed. These codes are what is causing your car to not perform well. The first thing you need to do is go over this guide which will most likely fix it:

https://www.2carpros.com/articles/throttle-actuator-service

and

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Once you perform this on your car get back to us with the code information and we can then properly diagnose your vehicle and send you tips on how to fix. Hope this helps and thanks for using 2CarPros.
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Friday, December 18th, 2020 AT 2:27 PM
Tiny
BEEPER76
  • MEMBER
  • 2003 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 221,000 MILES
The car will turn over but is not trying to start. The tach & other lights/gauges will not move. The check engine light& reduced power lights are on. Vehicle was at a cold start. Accelerator position sensor?
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Saturday, December 19th, 2020 AT 9:59 AM (Merged)
Tiny
HMAC300
  • MEMBER
Scan for codes to see why the lights are on might be a crank/cam sensor or something like that. Try resetting your security system. But with reduced power on and check engine something has failed.
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Saturday, December 19th, 2020 AT 9:59 AM (Merged)
Tiny
JAMES ARCHER
  • MEMBER
  • 2003 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 220,000 MILES
Replaced a fuel injector. Had to pull the intake manifold off to do it. Now the reduced power light is on. I have engine codes p1345 and p1514. What could I have done wrong?
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Saturday, December 19th, 2020 AT 9:59 AM (Merged)
Tiny
ROY B
  • EXPERT
Good morning.

The first thing I would check is the connector that goes to the throttle body. That is the sensor that controls the throttle. It is a very common failure the the connector and the throttle position sensor to be the failure.

Roy
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Saturday, December 19th, 2020 AT 9:59 AM (Merged)
Tiny
ROY B
  • EXPERT
More information. Check all connections to all sensors related to your repair.

Roy

P1345
Item description.
Symptom/dtc p1345.
Descriptor.
Probable causes:
Cam position sensor (cmp) actuator binding.
Camshaft phaser solenoid stuck.
Camshaft position actuator solenoid.
Harmonic balancer proper installation.
Mis-built or incorrectly timed engine.
P0014.
Valve timing correct.
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Saturday, December 19th, 2020 AT 9:59 AM (Merged)
Tiny
ROY B
  • EXPERT
More information.

Roy

P1514
Item description.
Symptom/dtc p1514.
Descripto.
Probable causes:
Air leaks.
Other dtcs.
Skewed cam sensor signal.
Throttle blade damage.
Throttle body.
Vacuum hose.
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Saturday, December 19th, 2020 AT 9:59 AM (Merged)
Tiny
DOSTROSK
  • MEMBER
  • 2003 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 175,000 MILES
Hi,
2003 Chevy Trailblazer-high miles well maintained. Reduced power light started coming on in January this year. Popped codes P1271 and sometimes P1275 and I replaced the accelerator position sensor. It is an intermittent problem where as it will not come on for a few days, then all of a sudden on a cold start it will come on. Shut off restart and comes on for three consecutive start cycles then fine. The TB runs fine no other issues but this code p1271 and reduced engine power light. Seems to do it primarily on a cold start. Replaced the throttle body and had GM dealer update the PCM with the newest software. Tried jiggling all of the connections to make the fault appear, but no luck. Everything looks intact. There was also a code for the camshaft position sensor and I replaced the sensor-code has not appeared for the CPS since replaced at the same time as the accelerator position sensor. Any ideas on where to look next?
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Saturday, December 19th, 2020 AT 9:59 AM (Merged)
Tiny
MERLIN2021
  • MEMBER
DTC P1271: ACCELERATOR PEDAL POSITION SENSORS 1 & 2 CORRELATION NOTE: To locate components, see COMPONENT LOCATIONS. For circuit reference, see WIRING DIAGRAMS. For connector terminal identification, see CONNECTOR IDENTIFICATION. Description The Accelerator Pedal Position (APP) sensors 1 and 2 are located within the accelerator pedal assembly. Each sensor has the following circuits: A 5-volt reference circuit. " A low reference circuit. " A signal circuit. " This provides the Powertrain Control Module (PCM) with a signal voltage proportional to accelerator pedal movement. The APP sensor 1 signal voltage at rest position is about the low reference and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position is about the 5-volt reference and decreases as the pedal is actuated. Conditions For Running DTC The battery voltage is more than 5.23 volts. " DTCs P1275, P1280, P1635, or P1639 not set. " The accelerator pedal is leaving the idle position. " Conditions For Setting DTC The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value. Action Taken When DTC Sets The control module illuminates the Malfunction Indicator Light (MIL) when the diagnostic runs and fails. " The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records. " The control module commands the TAC system to operate in the Reduced Engine Power mode; or, under certain conditions the control module commands the engine OFF. " The message center displays Reduced Engine Power. " Conditions For Clearing MIL/DTC PCM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and does not fail. " A History DTC clears after 40 consecutive warm up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic. " The scan tool clears the MIL/DTC. " Test Description The number below refers to the step number in the diagnostic procedures. 2 - Any circuit faults on either APP sensor 1 or 2 will set one of the DTCs listed. Refer to the appropriate test for diagnosis. Diagnostic Procedures Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. 1. Using scan tool, observe the DTC information. Is DTC P1120, P1220, P1275, P1280, P1635, or P1639 also set? If yes, see DTC P1120: THROTTLE POSITION SENSOR 1 CIRCUIT, DTC P1220: THROTTLE POSITION SENSOR 2 CIRCUIT, DTC P1275: ACCELERATOR PEDAL POSITION CIRCUIT (SENSOR 1), DTC P1280: ACCELERATOR PEDAL POSITION CIRCUIT (SENSOR 2), DTC P1635: 5-VOLT REFERENCE "A" CIRCUIT or DTC P1639: 5-VOLT REFERENCE "B" CIRCUIT. If no, go to next step. 2. Turn ignition off. Disconnect the APP sensor electrical connector. Disconnect the PCM. Use a DVOM to measure the resistance of the following circuits for each of the APP sensors: 3. Low reference circuit. " Signal circuit. " 5-volt reference circuit. " Did any of the circuits measure more than 5 ohms? If yes, go to step 5. If no, go to next step. Test for a short between any of the circuits in the APP sensor harness. Repair circuit as necessary. Did you find and correct the condition? If yes, go to step 7. If no, go to step 6. 4. Repair high resistance in the circuit. After repairs, go to step 7. 5. Replace APP sensor. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. After repairs, go to next step. 6. Clear the DTCs with scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions For Running DTC. See CONDITIONS FOR RUNNING DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step 2. 7. Observe the stored information, Capture Info with scan tool. Does scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS. If no, system is okay. 8. Diagnostic AidsThe PCM compares the signal of each of the accelerator pedal position sensors to each other throughout the entire range of operation. Clear the DTCs and actuate the pedal through the entire range with the ignition ON and engine OFF. Use the Connector Test Adapter Kit (J-35616-A) for any test that requires probing the PCM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals. If DTC is determined to be intermittent, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.2L BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article.
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Saturday, December 19th, 2020 AT 9:59 AM (Merged)
Tiny
TRAILBLAZER731
  • MEMBER
  • 2002 CHEVROLET TRAILBLAZER
  • 4.6L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 345,700 MILES
When the temperature is under 40 degrees my vehicle has a reduced engine power light. Once I warm up the truck is clear and ready to drive. Could you please point me in the right direction?
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Saturday, December 19th, 2020 AT 10:00 AM (Merged)
Tiny
ROY B
  • EXPERT
Good afternoon,

This could be a dirty throttle body.

https://www.2carpros.com/articles/reduced-power-limp-mode

I would suggest cleaning it and see if it still happens.

https://www.2carpros.com/articles/throttle-actuator-service

Also, can you see if there are any codes set? That will tell me if there is a electrical failure.

Roy
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Saturday, December 19th, 2020 AT 10:00 AM (Merged)
Tiny
TPAYNE3962
  • MEMBER
  • 2002 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 124,654 MILES
My reduced engine power light came on; i've been keeping the truck well maintained never had any bad problem; what can be the problem before I spend too much money trying to find the probklem and is the vehicle drivable while that light is on?
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Saturday, December 19th, 2020 AT 10:00 AM (Merged)
Tiny
ZACKMAN
  • MEMBER
We won't know until the PCM is scanned for codes. Some Autozone stores still perform this for free or you may inquire at CSK/O'Reilly stores to which repair facility that has agreed to perform this service for their customers. Each CSK/O'Reilly store has at least a shop that will do this for free.

Once you have the codes, post it here (code numbers, not descriptions). We will help with the diagnostics.

For as long as the light not not flashing, you are OK to drive.
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Saturday, December 19th, 2020 AT 10:00 AM (Merged)

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