P1125 On Chevrolet, the accelerator pedal position sensors are faulty or disagree

Accelerator pedal position system (APP sensor 1 and 2) fault

P1125 in short

On Chevrolet, P1125 points to the accelerator pedal position sensors: the computer sees circuit 1 or 2 as faulty or the two signals disagreeing. Likely causes are a worn pedal sensor or a wiring fault. Power may be limited, so get it checked soon. Other makes use P1125 differently.

Chevrolet trucks and SUVs from the early 2000s use a pedal assembly with more than one position sensor. P1125 is the manufacturer-specific code for a fault in that pedal position system. A Chevrolet service tip describes it as an APP sensor 1 and 2 circuit malfunction on a 2003 Silverado 2500HD.

GM published a bulletin in 2003 revising the P1125 description, and later bulletins list it with P2138 on the 2005 Equinox and with P2125 on the 2004 Express.

The code means different things on other makes: Toyota and Audi bulletins use it for unrelated faults, so this page speaks only for Chevrolet.

Pick your make

P1125 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

Most likely causes

  1. Faulty accelerator pedal position sensor assembly

    Supported by vehicle data
    Why it ranks here
    The Chevrolet service tip ties P1125 to the pedal sensors, and the Equinox bulletin pairs it with P2138, the pedal sensor correlation code.
    What would change this
    Rises if scan-tool APP 1 and 2 values disagree as you press the pedal. Falls if they track together.
    How to test the accelerator pedal position sensor

  2. Wiring, connector or reference-voltage fault in the APP circuits

    Common general cause
    Why it ranks here
    Open or shorted pedal circuits give the same fault and are cheaper to check first.
    What would change this
    Rises if wiggling the harness changes the readings. Falls if wiring tests clean.

  3. Model-specific GM service information

    Possible — needs testing
    Why it ranks here
    GM bulletins 030604031, 01912 and 3239 name P1125 but the NHTSA summaries do not state the repair.
    What would change this
    Rises if a dealer finds an applicable update or procedure for your VIN. Falls if none applies.
    How to test the engine control module (ecm / pcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all codes. Note P2138, P2125, P0121 or P0221 stored with P1125.

    Low riskTool: OBD-II scan tool

    • IfOther pedal or throttle codes are stored

      It meansCompare the pedal sensor readings.

      Go to step 2

    • IfP1125 alone

      It meansCompare the pedal sensor readings.

      Go to step 2

  2. Watch APP sensor 1 and 2 on a scan tool while pressing the pedal slowly.

    Low riskTool: scan tool with live data

  3. Ask a dealer whether a GM bulletin or update applies to your VIN.

    Low risk

Symptoms

  • Check engine light, sometimes with a reduced-power message
  • Weak or delayed acceleration
  • Engine stalls or loses power in traffic Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

  1. With the engine off, check the pedal sensor connector for loose or corroded pins and reseat it.

  2. Ask a dealer about GM bulletins that apply to your VIN.

Parts and cost context

  • Accelerator pedal position sensor:Usually sold as a complete pedal assembly. Confirm with live data first.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2003 · Avalanche

    Supported by vehicle data

    GM bulletin 030604031 revised the P1125 definition for 2003 trucks and SUVs. Not verified as current.

  • 2005 · Equinox

    Supported by vehicle data

    GM bulletin 01912 covers a check engine light on the 2005 Equinox with P1125 or P2138. Not verified as current.

  • 2004 · Express

    Supported by vehicle data

    GM bulletin 3239 covers a warning light on the 2004 Express with P1125 and P2125. Not verified as current.

  • 030604031Status unverified

    Revised diagnostic trouble code P1125

    2003avalanche, tahoe, trailblazer, suburban · issued · NHTSA 10002858

    GM revised the P1125 diagnostic description for 2003 trucks and SUVs. The NHTSA summary does not give a repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 01912Status unverified

    MIL on with P1125 or P2138

    2005equinox · issued · NHTSA 10006817

    Covers a check engine light on the 2005 Equinox with P1125 or P2138, or both.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 3239Status unverified

    Light on with P1125 and P2125

    2004express · issued · NHTSA 10010657

    Covers a warning light on the 2004 Express with P1125 and P2125 set.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P2138Two accelerator pedal position sensor signals (D and E) that should agree with each other don't

    Same system Supported by vehicle data

    GM lists P2138 with P1125 on the 2005 Equinox for the same pedal sensor system.

  • P0121The throttle position sensor A signal doesn't agree with what the engine computer expects, even though the voltage is within range

    Same system Common general cause

    P0121 is the standard throttle/pedal range code that sits in the same circuit family.

All Electronic throttle and accelerator pedal codes

P1125 questions

Does P1125 mean the same on every car?

No. It is a manufacturer-specific code. On Chevrolet it is an accelerator pedal position fault; Toyota and Audi use it differently.

Sources and review

  1. Chevrolet 01912: MIL on with P1125 or P2138 — NHTSA manufacturer communications ,
  2. Chevrolet 3239: Light on with P1125 and P2125 — NHTSA manufacturer communications ,
  3. P1125 DTC: accelerator pedal position sensors 1 and 2 circuit malfunction (2003 Chevrolet Silverado 2500HD 6.0L) — International Automotive Technicians Network
  4. P1125 trouble code explanation — TroubleCodes.net
  5. Chevrolet 030604031: Revised diagnostic trouble code P1125 — NHTSA manufacturer communications ,
Last reviewed
Written by
Saurabh K.
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