P2125 on 2007-2014 Cadillac Escalade ESV: Reduced Power and APP Sensor Fixes

What's Unique About the 2007-2014 Cadillac ESCALADE ESV

On this generation of GM trucks and SUVs (GMT900 platform), wiring issues are a well-documented cause for accelerator pedal codes. A manufacturer Technical Service Bulletin (PIP3783D) specifically advises technicians to check for poor electrical contact (terminal tension) at the APP sensor connector before replacing parts. This TSB also points to other potential wiring problem spots, like the C109/X109 connector below the underhood fuse block. This means a simple, no-cost connector fix can often resolve a problem that might otherwise lead to an unnecessary and expensive pedal replacement.

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 dashboard
• Check Engine Light (Service Engine Soon lamp) is on.
• Poor or no throttle response.
• Vehicle will not accelerate past a low speed (limp mode).
• Hesitation or stalling when pressing the accelerator.
• "Service Stabilitrak" message may also appear.

Most Likely Causes

1. Poor Terminal Tension at APP Sensor Connector 🔴 High Probability This is a known issue documented by GM in Technical Service Bulletin #PIP3783D for this vehicle platform. The connector is in the driver's footwell and can be disturbed by feet or floor mats.
   How to confirm: With the key on, gently wiggle the wiring harness connector at the accelerator pedal. If this action causes the fault to appear or disappear, or if the connector feels loose, poor terminal tension is the likely cause. A user on a Tahoe forum fixed his issue by simply unplugging, cleaning, and re-plugging the connector. 🎬 Watch: A simple guide to cleaning and fixing the connector.
   Typical fix: Disconnect the battery, then the connector. Use a small pick tool to carefully tighten the female pin terminals within the connector to ensure a snug fit on the sensor pins. Apply a small amount of dielectric grease before reconnecting.
   Est. part cost: $0-$25
2. Failed Accelerator Pedal Position (APP) Sensor 🟡 Medium Probability → Shop Accelerator Pedal Assembly The electronic sensors integrated into the pedal assembly can wear out over time, leading to erratic signals. This is a very common failure point on GMT900 trucks.
   How to confirm: Using a scan tool, monitor the live data for APP Sensor 1 and APP Sensor 2 voltage while slowly pressing and releasing the pedal. The voltage readings should be smooth and consistent, with no dropouts or spikes. A jumpy or flat reading on APP Sensor 2 specifically points to a failed sensor that would cause P2125.
   Typical fix: Replace the entire accelerator pedal assembly. It is a single unit that contains the sensors and is typically held on by two or three nuts. 🎬 See this walkthrough on replacing the entire pedal assembly.
   Est. part cost: $80-$160
3. Damaged Wiring Harness ⚪ Low Probability The harness leading to the pedal can be kicked, stretched, or chafed over time, causing an open or short in a wire. A YouTube video on a platform-mate Silverado showed a broken ground wire near the passenger side of the intake manifold causing identical symptoms. A separate documented case found the harness chafed through on a valve cover.
   How to confirm: Visually inspect the entire length of the wiring harness from the pedal to where it enters the main loom. Look for any signs of physical damage, melting, or corrosion. Perform a continuity test on each wire between the APP sensor and the PCM if no visual damage is found. TSB PIP3783D also suggests checking connectors C109/X109 and C205/X205 for issues.
   Typical fix: Repair the specific damaged section of wire using solder and heat shrink for a durable fix.
   Est. part cost: $5-$25

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is extremely rare and should only be considered after the APP sensor, its connector, and all related wiring have been definitively ruled out as the cause.

Diagnosis Steps

1. Read all stored fault codes with an OBD-II scanner. Note any other codes that appear with P2125, such as P2138 or P2120.
2. Visually inspect the accelerator pedal's wiring connector for looseness or obvious damage. Check that it's fully seated.
3. As per TSB #PIP3783D, carefully check the female terminals in the connector for poor tension. Wiggle the harness with the key on to see if the fault is intermittent.
4. Using a scan tool's live data function, observe the voltage readings from 'APP Sensor 1' and 'APP Sensor 2' as you slowly depress the pedal. Look for smooth, linear changes. For P2125, the issue will be with the APP Sensor 2 signal, which should be between 0.24V and 4.49V.
5. If the live data for APP Sensor 2 shows a drop-out, spike, or is stuck, and the connector is confirmed to be tight and clean, the accelerator pedal assembly is the most likely culprit.
6. If the sensor and connector seem fine, inspect the wiring harness for damage. Pay close attention to the area in the footwell and check other connectors like C109/X109 as mentioned in the TSB.
7. Perform continuity and voltage drop tests on the wires between the APP sensor and the PCM to find any hidden breaks or shorts.

Parts You'll Likely Need

• Accelerator Pedal Assembly (OEM #25832864) — This assembly contains the non-serviceable electronic sensors that fail. It is the most common part replaced to fix this code after wiring is checked. Note that part number 25832864 may be superseded by newer numbers, so always verify with your VIN.
  Trusted brands: ACDelco (GM Genuine), Delphi, Dorman (e.g., 699-105)
  OEM price range: $110-$162
  Aftermarket price range: $50-$90

Related Codes That Often Appear With This One

• P2138 — This code indicates a correlation problem between APP Sensor 1 and APP Sensor 2. A fault in one sensor's circuit (triggering P2125) will cause its signal to disagree with the other, triggering P2138.
• P2120 — This is another circuit-specific code for the APP sensor assembly, but it relates to APP Sensor 1. A wiring or connector issue can often affect multiple circuits simultaneously, causing both codes to appear.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #PIP3783D: Advises technicians to inspect the Accelerator Pedal Position (APP) sensor circuits for poor terminal tension when encountering DTCs P2120, P2122, P2123, P2125, P2127, P2128, and/or P2138. It also suggests checking other harness connectors (C109/X109, C205/X205) if the pedal connector is good.

Platform-Specific Known Issues

• As documented in GM Technical Service Bulletin #PIP3783D, these vehicles are known to have issues with poor terminal tension in the accelerator pedal position sensor connector, which directly causes code P2125 and the associated 'Reduced Engine Power' mode.
• A user on the 'Chevrolet Forum' with a 2008 Tahoe (a platform mate) experienced the 'Service Stabilitrack' and 'Reduced Engine Power' messages, which are commonly associated with this failure.
• A YouTube video from channel '1A Auto' lists 'Engine Reduced Power Mode' as one of the top 5 problems with this generation of Escalade, explicitly mentioning the accelerator pedal sensor as a primary cause.

Mechanic-Grade Diagnostic Values

• APP Sensor 2 Signal Voltage — expected: 0.24V - 4.49V (Key On, Engine Off, varies with pedal press). Failure: Voltage is less than 0.24V or more than 4.49V for more than 0.5 seconds.
• APP Sensor 5-Volt Reference Circuit Voltage — expected: 4.8V - 5.2V (at pedal connector, Key On). Failure: Voltage is outside this range, indicating a problem with the PCM or wiring.
• APP Low Reference Circuit Resistance — expected: Less than 3.0 ohms (between APP connector low reference pins and chassis ground). Failure: Resistance is higher than 3.0 ohms, indicating a poor ground connection.

Hidden / Shadow Codes Worth Checking

• DTC Symptom Byte: While not a separate code, a GM dealer scan tool (Tech2/GDS2) will display a 'symptom byte' alongside P2125. This provides more detail, such as 'Circuit Low Voltage' or 'Circuit High Voltage', which helps a technician immediately know whether to look for a short to ground or a short to power/open circuit. (see via GM Tech2 or GDS2 diagnostic scan tool.)

Scan Tool Commands That Help

• Manual Procedure (No Tool Required): Accelerator Pedal Position Relearn — After replacing the accelerator pedal assembly or disconnecting the battery. While not always mandatory as the system can self-learn, this can resolve erratic idle or response issues more quickly. The procedure typically involves turning the key to 'ON' (engine off), slowly pressing the pedal to the floor, slowly releasing it, then turning the key 'OFF'.
• GDS2 / Professional Scan Tool: ETC Relearn / Throttle Relearn — After replacing the accelerator pedal or throttle body. This function resets all learned values for the electronic throttle control system, ensuring the new components work correctly with the PCM.

Wiring & Ground Locations

• APP Sensor Connector Pinout — At the top of the accelerator pedal assembly in the driver's footwell.. Knowing the specific function of each pin is critical for testing. P2125 relates to APP Sensor 2. Pin B is the signal, Pin A is the low reference, and Pin C is the 5V reference for that sensor.
• APP Connector Pin B — Light Blue wire, Circuit #1162. This is the APP Sensor 2 Signal wire. A short or open on this specific wire will directly cause P2125.
• G103 / G104 — G103 is on the front of the driver's side cylinder head. G104 is on the rear of the driver's side cylinder head.. These are primary engine-to-chassis grounds. A poor connection at these points can cause floating ground issues and erratic voltage readings for many sensors, including the APP sensor which is grounded through the PCM.
• Block-to-Chassis Ground Strap — Typically runs from the rear of the passenger side cylinder head/block to the firewall/chassis.. This is a known failure point on GMT900 trucks. The strap can corrode and break, causing a host of electrical issues, including APP sensor codes, due to the engine and body having different ground potentials.

Real Owner Repair Stories

• YouTube video on a GM vehicle with 3.8L engine (GM vehicle with drive-by-wire throttle) — Reduced Engine Power message, codes P1125, P2125, P2138.
  ❌ Tried (didn't work) Replacing the accelerator pedal assembly, Replacing the throttle body
  ✅ What actually fixed it The wiring harness was found to be rubbing against the edge of a valve cover, which had worn through the insulation on multiple wires and caused them to short out. The fix was to repair the damaged wires and protect the harness from future chafing.

When the Usual Fixes Don't Work

• While the most common fixes for P2125 are the APP sensor connector (per TSB PIP3783D) or the pedal assembly itself, there are documented cases where neither was the cause. In one instance, a vehicle with identical symptoms and codes was only fixed after discovering a section of the main engine wiring harness had chafed through on a valve cover, causing a short circuit. This highlights the need to consider the entire circuit, including harness routing in the engine bay, if the obvious fixes don't work.

OEM Part Supersession History

• 15101848, 15847349 → 25832864 — Standard part evolution and consolidation by the manufacturer.
  Heads up: These part numbers are for models with power-adjustable pedals. Always verify by VIN.

Model Year Variations Within This Range

• 2007-2011: The common replacement part number 25832864 is most frequently cited for the 2007-2011 model years. Owners of 2012-2014 models should take extra care to verify the correct part number for their specific vehicle using the VIN, as a different part may be used in later years of the generation.