P2125 on 2007-2013 Chevrolet Avalanche: Accelerator Pedal Sensor Circuit Fault and Fixes

What's Unique About the 2007-2013 Chevrolet AVALANCHE

On this generation of GM trucks (GMT900 platform), a very common cause for P2125 is poor electrical contact in the accelerator pedal's connector. GM issued Technical Service Bulletin #PIP3783D specifically advising technicians to inspect for poor terminal tension in the APP sensor circuits before replacing any parts. This means a simple 'wiggle test' of the connector could diagnose the problem and potentially save you from buying a part you don't need. Forum users have reported that simply unplugging, cleaning, and securely reconnecting the pedal connector can resolve the issue.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• "Reduced Engine Power" message displayed on the instrument cluster.
• Check Engine Light (Malfunction Indicator Lamp) is on.
• Poor or no throttle response.
• Vehicle may feel sluggish or unable to accelerate properly.
• Vehicle may stall or have a rough idle.
• "Service StabiliTrak" and "Service Traction Control" messages may also appear.

Most Likely Causes

1. Faulty Accelerator Pedal Position (APP) Sensor Assembly 🔴 High Probability The electronic sensors within the pedal assembly can wear out over time from constant use, leading to erratic, dead spots, or out-of-range voltage signals.
   How to confirm: Using a scan tool, monitor the live data for APP Sensor 2. If the voltage is stuck, jumps erratically when the pedal is pressed, or reads outside the specified range (e.g., below 0.24V or above 4.49V), the sensor is bad. The voltage should sweep smoothly up and down as you press and release the pedal.
   Typical fix: Replace the entire accelerator pedal assembly. The sensor is integrated into the pedal unit and is not sold separately. This is a plug-and-play part requiring no special programming. 🎬 Watch: Step-by-step walkthrough for replacing the pedal assembly.
   Est. part cost: $60-$150
2. Poor Wiring Connection or Terminal Tension at the APP Sensor 🟡 Medium Probability As documented in TSB #PIP3783D, the connector terminals for the APP sensor can become loose, causing intermittent signal loss. The connector is also in the footwell, where it can be kicked, stressed by floor mats, or exposed to moisture from wet shoes or a water leak.
   How to confirm: With the ignition on, wiggle the connector and wiring harness at the accelerator pedal while observing the APP sensor voltage on a scan tool. If the voltage fluctuates wildly or the code sets, the connection is the problem. Also, visually inspect the connector pins for corrosion or being spread too far apart.
   Typical fix: Disconnect the connector, inspect for corrosion or spread/loose pins. Clean the terminals with electronic contact cleaner and apply dielectric grease. If terminals are loose, they may need to be carefully re-tensioned or the connector pigtail may need to be replaced. Common pigtail part numbers include ACDelco PT2712 and Dorman 645-595.
   Est. part cost: $0-$40
3. Damaged Wiring Harness ⚪ Low Probability The wiring harness can be damaged from abrasion against sharp edges under the dash, from being pinched, or from rodent damage, especially if a grommet is dislodged. In some cases, water intrusion into other dash connectors can cause this code.
   How to confirm: Perform a continuity and resistance test on the signal, reference, and ground wires between the PCM connector and the APP sensor connector. Check for opens, shorts to ground, or shorts to power. A visual inspection may reveal chafed or broken wires.
   Typical fix: Repair the specific broken or shorted wire in the harness. This may involve soldering in a new section of wire and using heat shrink tubing for a durable, moisture-proof repair.
   Est. part cost: $5-$25

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): This is extremely rare and should only be considered after the APP sensor, connector, and all related wiring have been proven to be good. A failed self-test of the throttle inputs using a bi-directional scanner can point to an internal PCM fault.

Diagnosis Steps

1. Connect an OBD-II scanner and confirm P2125 is present. Note any other related codes like P2138.
2. Check for relevant Technical Service Bulletins (TSBs). For this issue, TSB #PIP3783D is critical and advises checking terminal tension first.
3. Visually inspect the accelerator pedal's electrical connector and wiring harness for any obvious damage, corrosion, or loose connections. Ensure floor mats are not interfering with the pedal or wiring.
4. With the key on and engine off, use a scan tool to view live data for APP Sensor 1 and APP Sensor 2.
5. Slowly press and release the accelerator pedal. Both sensor voltage readings should change smoothly without glitches or dropouts. P2125 points to a problem with Sensor 2 🎬 See how to use wiring diagrams to pinpoint the fault. ('E' circuit).
6. Perform a 'wiggle test': while watching the live data, gently wiggle the connector and harness at the pedal. If the voltage readings become erratic, the problem is in the wiring or connector.
7. If the wiring and connector are good but the Sensor 2 voltage is stuck, erratic, or out of range, the accelerator pedal assembly is faulty and needs to be replaced.
8. If a new pedal does not fix the issue, perform a detailed circuit integrity test (checking for continuity, shorts, and resistance) on the wires between the APP sensor connector and the PCM.

Parts You'll Likely Need

• Accelerator Pedal with Position Sensor (OEM #25832864) — This is the most common failure point for code P2125. The sensor is integrated into the pedal assembly and is replaced as a single unit. This part number supersedes older numbers 15847349 and 15101848.
  Trusted brands: ACDelco, Standard Motor Products, Dorman, NGK
  OEM price range: $100-$150
  Aftermarket price range: $60-$120
• APP Sensor Connector Pigtail (OEM #ACDelco PT2712 / GM 13584094) — If the connector itself is damaged or the terminals have lost tension and cannot be repaired, replacing the pigtail is the correct fix. This is the second most common repair after the pedal assembly itself.
  Trusted brands: ACDelco, Dorman (645-595), Standard Motor Products (S-1479)
  OEM price range: $20-$40
  Aftermarket price range: $10-$30

Related Codes That Often Appear With This One

• P2138 — This code indicates a voltage correlation problem between APP Sensor 1 and APP Sensor 2. It's very common to see with P2125 as they are both part of the same assembly and are often triggered by the same root cause (bad pedal, connector, or wiring).
• P2120, P2122, P2123, P2127, P2128 — These are all specific circuit fault codes (low or high voltage) for the two APP sensors. They are all mentioned in TSB #PIP3783D and point to the same potential wiring and sensor issues.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #PIP3783D: Addresses multiple APP sensor codes (including P2125) and advises technicians to inspect the accelerator pedal position circuits for poor terminal tension before replacing parts.

Platform-Specific Known Issues

• A known issue on the GMT900 platform (which includes the 2007-2013 Avalanche) is poor terminal tension in the accelerator pedal position sensor connector, as documented by GM in Technical Service Bulletin #PIP3783D.
• Forum discussions for platform-mate vehicles like the Silverado and Tahoe frequently mention that moisture getting into the driver's side footwell can corrode the main instrument panel-to-body harness connectors, leading to this and other electrical faults.

Mechanic-Grade Diagnostic Values

• APP Sensor 2 Signal Voltage — expected: Smooth sweep from ~0.24V to ~4.49V as pedal is pressed.. Failure: Voltage is less than 0.24V or more than 4.49V for more than 0.5 seconds.
• APP Sensor 5-Volt Reference Voltage — expected: Between 4.5V and 5.2V.. Failure: Voltage is less than 4.54V or more than 5.21V.

Scan Tool Commands That Help

• Manual Procedure (No Scan Tool): Idle Learn / Throttle Relearn Procedure — After replacing the accelerator pedal assembly or disconnecting the battery, this procedure helps the ECM relearn the new sensor's idle and range values, preventing a high or unstable idle. Start and idle the engine in PARK for 3 minutes. Turn the ignition OFF for 60 seconds. Start and idle the engine again in PARK for 3 minutes. The idle should now be stable.

Wiring & Ground Locations

• APP Sensor Connector (6-Pin) — At the top of the accelerator pedal assembly in the driver's footwell.. This is the primary connection point. P2125 relates to Pin B (APP Sensor 2 Signal). A pinout based on similar GM models is: Pin A=Low Ref 2, Pin B=Signal 2, Pin C=5V Ref 2, Pin D=Low Ref 1, Pin E=Signal 1, Pin F=5V Ref 1.
• G103 / G104 / G106 — These are primary engine block grounds. G103 is often on the front of the right cylinder head, G104 on the left rear, and G106 on the right front of the engine block.. The PCM and its sensors rely on clean ground connections. A corroded or loose engine ground can introduce electrical noise and cause erratic sensor readings, including the APP sensor.
• PCM Ground — A critical ground wire that runs from the main wiring harness to a bolt on the top rear of the engine block, often near the driver's side cylinder head.. This is the main ground for the Powertrain Control Module. A fault here can cause numerous sensor codes, including P2125, and is a frequently overlooked point of failure.

When the Usual Fixes Don't Work

• While the most common fixes for P2125 are replacing the accelerator pedal assembly or its connector pigtail, a significant number of owners have found these repairs do not solve the problem. In these cases, the root cause was often found to be water intrusion in the driver's side footwell. Leaks from a bad windshield seal, door weatherstripping, or clogged cab vents can allow water to saturate connectors near the floor. This moisture causes corrosion in the main body harness connectors, creating intermittent opens or shorts that can trigger a P2125 code, even though the pedal and its direct connector are perfectly fine. If replacing the pedal doesn't fix the issue, the next step should be to pull back the driver's carpet and inspect for any signs of past or present water damage.

OEM Part Supersession History

• 15101848, 15847349 → 25832864 — Standard part design updates and consolidation by GM.
  Heads up: The replacement part 25832864 is the correct service part for the entire 2007-2013 range.