P2127 on 2015-2019 Ram 3500: Accelerator Pedal Sensor 'E' Circuit Low Causes and Fixes

What's Unique About the 2015-2019 Ram 3500

On this generation of Ram Heavy Duty trucks, failure of the accelerator pedal assembly is a well-documented and common issue. The symptoms often appear suddenly, with the truck immediately entering a reduced-power 'limp mode'. Manufacturer Technical Service Bulletins (TSBs) for this platform specifically warn technicians that the code can be set accidentally if the pedal connector is unplugged during other diagnostic work, so it's crucial to confirm the code is active 🎬 See how to fix common gas pedal sensor codes. before replacing parts. [Bulletin #9004225, Bulletin #9003413]

Diagnostic Flowchart

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

Generation note: The 2015-2019 year range covers the end of the fourth generation (2010-2018) and the start of the fifth generation (2019). While the pedal assembly is a common failure point on both, the part numbers may differ, especially between trucks with and without power-adjustable pedals. Always verify the part by VIN. The 2019 model year was a split, with the new 5th generation being a significant redesign (new frame, interior, and Cummins engine updates) while the 4th generation body style continued to be sold.

Symptoms You May Notice

• Check Engine Light is on
• Electronic Throttle Control (ETC) warning light illuminated (red lightning bolt symbol)
• "Service Electronic Throttle Control" message on the dashboard
• Vehicle enters 'limp mode' with drastically reduced engine power and speed
• Little to no throttle response (a 'dead pedal')
• Hesitation or surging during acceleration
• Engine randomly cuts out while driving but doesn't die, requiring you to lift off the pedal and press again to regain response.

Most Likely Causes

1. Faulty Accelerator Pedal Position Sensor (APPS) Assembly 🔴 High Probability The integrated electronic sensor within the pedal assembly is a very common failure point on this platform, with numerous owner accounts confirming replacement as the fix.
   How to confirm: Use a scan tool to monitor live data for APP Sensor 1 and APP Sensor 2. As you press the pedal, the voltage for both should rise smoothly. If Sensor 2's voltage is stuck low (typically near 0V) or doesn't respond, the sensor is bad.
   Typical fix: Replace the entire accelerator pedal assembly. It is a single unit that includes the integrated sensor and is held on by two 10mm nuts.
   Est. part cost: $200-$250
2. Wiring Harness or Connector Issue 🟡 Medium Probability The wiring to the pedal can be stressed or damaged. TSBs for this vehicle specifically highlight the need to check wiring and connectors before replacing the pedal. [Bulletin #9004225, Bulletin #9003413] One owner on Reddit found their issue was a poor connection at the large C130 bulkhead connector in the engine bay, which was resolved by reseating and tightening it.
   How to confirm: Visually inspect the wiring harness leading to the accelerator pedal for any signs of damage, chafing, or corrosion. Disconnect the connector and check for bent or corroded pins. Perform a 'wiggle test' on the harness and major connectors like the C130 while watching live data to see if the signal fluctuates.
   Typical fix: Repair the damaged section of wire or clean/replace the connector pigtail.
   Est. part cost: $10-$50
3. Powertrain Control Module (PCM) Fault ⚪ Low Probability
   How to confirm: This is a last resort after definitively ruling out the pedal assembly and all related wiring. A professional shop would need to perform advanced diagnostics to confirm a PCM driver circuit failure. In some rare cases, a short in another 5-volt reference circuit, like one for a transmission solenoid, can damage the PCM and cause this code.
   Typical fix: Replace and program the PCM.
   Est. part cost: $500-$1000

Rare But Worth Checking

• Aftermarket Performance Tuner/Pedal Modifier: Devices like a 'Pedal Commander' that plug in-line with the accelerator pedal can fail and cause these exact symptoms and codes. One owner on RamForum.com reported this issue started after installing a Pedal Commander. Even after removing the device, replacing the pedal, and replacing the throttle body, the code persisted. The final fix was a new PCM, suggesting the aftermarket device may have caused permanent damage to the module.

Diagnosis Steps

1. Scan for all diagnostic trouble codes. Note any other codes that appear with P2127, such as P2122 or P2138.
2. Visually inspect the wiring harness and connector at the accelerator pedal. Look for any obvious damage, loose connections, or corrosion. Check that the red locking tab on the connector is secure.
3. Using a scan tool, view the live data for 'APP Sensor 1' and 'APP Sensor 2'. The voltage for both should be low when the pedal is at rest and rise smoothly and in correlation as you press the pedal.
4. Confirm that the voltage for APP Sensor 2 is stuck at a very low value (e.g., below 0.25 volts) and does not change when the pedal is pressed.
5. If the signal is bad, perform a 'wiggle test' on the harness while watching the live data. If the voltage jumps around, a wiring fault is likely. Wiggle the connector at the pedal and also the main engine harness connectors (like the C130 bulkhead connector).
6. If the wiring appears intact and the signal is consistently bad, the accelerator pedal assembly is the most probable cause of failure.
7. After replacement, perform a pedal calibration procedure. This can be done without tools by turning the key to 'ON' (engine off), waiting for dash lights to cycle, slowly pressing the pedal to the floor, holding for 10 seconds, slowly releasing it, waiting another 10 seconds, and then turning the key 'OFF' before starting the engine.

Parts You'll Likely Need

• Accelerator Pedal Assembly (OEM #68163998AC (Fixed Pedals) or 68194932AC (Power-Adjustable Pedals)) — This is the most common failure item for code P2127. The sensor is integrated into the pedal assembly and is not sold separately. You must verify if you have fixed or power-adjustable pedals before ordering.
  Trusted brands: Mopar
  OEM price range: $200-$275
  Aftermarket price range: $100-$180

Related Codes That Often Appear With This One

• P2122 — P2122 is 'APP Sensor 1 Circuit Low'. Since the pedal has two sensors, it's common for both to be flagged when a major fault occurs. The TSBs mention them together. [Bulletin #9004225, 22]
• P2138 — P2138 is 'APP Sensor 1/2 Correlation'. This code sets when the signals from the two sensors don't match each other, which can happen when one sensor circuit fails (as indicated by P2127).
• P2299 — P2299 is 'Brake Pedal Position / Accelerator Pedal Position Incompatible'. The TSBs mention this code can be set alongside pedal faults. It often occurs if the brake and accelerator are pressed simultaneously, which the system flags as an error. [Bulletin #9004225, Bulletin #9003413]

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #9004225: Notes that P2127 can be set if the pedal is disconnected during diagnosis and to check wiring before replacement.
• Bulletin #9003413: Similar to the above, advises following diagnostic procedures and checking wiring/connectors before replacing the pedal for a P2127 code.

Platform-Specific Known Issues

• Accidental Code Setting: TSBs #9004225 and #9003413 explicitly state that P2127 can be set if the accelerator pedal connector is disconnected during diagnosis for other issues. It is critical to ensure the code is active and not a stored remnant of previous work before replacing parts.
• Adjustable vs. Fixed Pedals: These trucks were available with and without power-adjustable pedals. The accelerator pedal assemblies are NOT interchangeable. You must order the correct part for your truck's specific configuration. The Mopar part for fixed pedals is typically #68163998AC, while the part for power-adjustable pedals is #68194932AC.

Mechanic-Grade Diagnostic Values

• APPS 5-Volt Supply at Pedal Connector — expected: 4.5 to 5.2 volts with ignition on, engine off.. Failure: Voltage below 4.5V indicates an issue with the supply circuit from the PCM.
• APPS Sensor 2 Signal Voltage (Scan Tool) — expected: Should sweep smoothly as the pedal is pressed. The raw voltage of APP Sensor 2 is approximately half that of APP Sensor 1.. Failure: Voltage is consistently below 0.25 volts, triggering the P2127 code.
• APPS Sensor 2 Signal Circuit Resistance to Ground — expected: Greater than 100k ohms.. Failure: Resistance less than 100k ohms indicates a short to ground in the signal wire.
• APPS Sensor 2 Signal Circuit Continuity — expected: Less than 10 ohms between the pedal connector and the PCM connector.. Failure: Resistance greater than 10 ohms indicates an open or high resistance in the signal wire.

Wiring & Ground Locations

• Accelerator Pedal Connector (C201) — Directly connected to the top of the accelerator pedal assembly under the driver's side dashboard.. This is the primary connection point for the sensor. Loose pins, corrosion, or harness damage here are common causes of the fault. It contains the 5V supply, ground, and two signal return wires to the PCM.
• PCM Connector C1, Pin 91 — On the Powertrain Control Module (PCM), typically located in the engine bay.. This is the specific pin where the APP Sensor 2 signal (Circuit K29, WT/BR wire) terminates. Testing continuity and for shorts to ground/power should be done between this pin and the pedal connector.
• PCM Connector C1, Pin 69 — On the Powertrain Control Module (PCM) in the engine bay.. This is the 5-Volt Supply pin (Circuit K854, VT/BR wire) that provides reference voltage to the accelerator pedal sensor.
• PCM Connector C1, Pin 42 — On the Powertrain Control Module (PCM) in the engine bay.. This is the Sensor Ground pin (Circuit K914, BR/WT wire) for the accelerator pedal sensor. A bad ground connection here can cause erratic voltage readings.

Real Owner Repair Stories

• RamForum.com user Chasehamaker17 (2012 Ram 5.7L (similar 5V reference system)) — P2127 code, ETC light flashing, truck in limp mode.
  ❌ Tried (didn't work) Removing an aftermarket Pedal Commander., Replacing the accelerator pedal assembly., Replacing the throttle body.
  ✅ What actually fixed it The 5-volt reference circuit for the transmission solenoid was shorting out. After cleaning the connector provided a temporary fix, the ultimate solution was replacing the PCM, which had likely been damaged by the short.
• RamForum.com user Lancem86 (2017 Ram 1500 Tradesman) — P2127 and P2138 codes with red lightning bolt, occurring specifically after making left turns.
  ❌ Tried (didn't work) Replacing the throttle body., Installing a new accelerator pedal.
  ✅ What actually fixed it The user reinstalled the original OEM accelerator pedal and performed a pedal/TPS recalibration procedure. This suggests the new (potentially aftermarket) pedal was faulty or incompatible.

OEM Part Supersession History

• 68194932AA, 68194932AB → 68194932AC — Standard part revision and update by the manufacturer.
  Heads up: This part is for trucks with power-adjustable pedals only and is not interchangeable with the fixed pedal assembly.

Model Year Variations Within This Range

• 2019: The 2019 model year is a transition year. The 'Ram 1500 Classic' and all 2500/3500 models retained the 4th generation platform. The all-new 5th generation Ram 1500 (Designation DT) was introduced with a completely new frame, cab interior, and updated electronics. The 2500/3500 models transitioned to the 5th generation for the 2019 model year, featuring a new CGI engine block and CP4 injection pump for the Cummins engine (later recalled).