P20E2 — Exhaust Gas Temperature Sensor 1/2 Correlation #

Note: The description for this code may vary depending on the vehicle manufacturer.

• Exhaust Gas Temperature Sensor 1/2 Correlation (General / SAE)
• EGT Sensor 1/2 Signal Implausible (Volkswagen/Audi)
• Exhaust Gas Temp Sensor 1/2 Comparison Fault (Ford)
• EGT Sensor Bank 1 Sensor 2 Correlation (GM/Chevrolet)

Summary of Code P20E2 #

Diagnostic Trouble Code (DTC) P20E2 indicates a correlation issue between the readings of Exhaust Gas Temperature (EGT) Sensor 1 and Exhaust Gas Temperature Sensor 2. These sensors are critical for monitoring the temperature of exhaust gases, especially in vehicles equipped with Selective Catalytic Reduction (SCR) or Diesel Particulate Filter (DPF) systems. When the Engine Control Module (ECM) or Powertrain Control Module (PCM) detects that these two sensors are reporting temperatures that are not within a specified range of each other, it sets code P20E2. This code can directly impact emission control and engine protection strategies. Prompt diagnosis is important to avoid potential damage to aftertreatment components and to remain compliant with emission standards.

Common Symptoms for Code P20E2 #

A P20E2 code may not always trigger noticeable drivability issues initially. However, as the system detects ongoing discrepancies, you may observe signs indicating exhaust temperature sensor problems or aftertreatment system malfunction. Typical symptoms include:

• Illuminated Check Engine Light (CEL or MIL)
• SCR or DPF system warning indicators on the dashboard
• Reduced engine power (limp mode) in severe cases
• Increase in exhaust smoke (especially with DPF issues)
• Poor fuel economy due to incorrect exhaust temperature readings
• Difficulty performing forced DPF regen (diesel models)

Probable Causes for Code P20E2 #

Several issues can cause the ECM/PCM to detect an exhaust gas temperature sensor correlation fault. The most common causes, in order of frequency, are:

1. Faulty EGT Sensor 1 or Sensor 2 (open circuit, short, or drifted calibration)
2. Wiring issues (damaged, corroded, or loose connectors/wires between sensor and ECM/PCM)
3. Exhaust leaks near the sensor locations, causing abnormal temperature readings
4. Failed or contaminated aftertreatment components (such as SCR or DPF malfunction)
5. Software or calibration errors within the ECM/PCM, though less common

Step-by-Step Diagnostic for Code P20E2 #

To accurately diagnose a P20E2 code, follow these logical steps. Proper diagnosis prevents unnecessary parts replacement and ensures the root cause is addressed:

• Confirm the code. Use a compatible scan tool to read current and pending codes, and note freeze frame data.
• Visually inspect the EGT sensors and their wiring for damage, corrosion, or loose connectors.
• Check for exhaust leaks around the sensor mounting points and repair if found.
• Use scan tool live data to compare EGT Sensor 1 and Sensor 2 readings at cold start and at operating temperature.
• Test sensor resistance (with multimeter) according to OEM specifications, both at ambient and after warming up the exhaust.
• Backprobe sensor signals at the ECM/PCM to rule out wiring/connector issues.
• Check for any relevant TSBs (Technical Service Bulletins) or software updates from the OEM.

Possible Repairs for Code P20E2 #

Repair strategies depend on the confirmed cause. Always address the root issue rather than just clearing the code:

• Replace the faulty EGT sensor (Sensor 1 or Sensor 2) if out of specification or non-responsive
• Repair or replace damaged wiring/connectors between the sensor and ECM/PCM
• Seal or repair exhaust leaks near sensor locations
• Replace or service aftertreatment components (DPF, SCR) if found to be malfunctioning
• Update ECM/PCM software if a known issue or TSB exists

Is It Safe to Drive with Code P20E2? #

Limited: While you may be able to drive with a P20E2 code for a short period, it is not advisable to ignore it. The code often leads to reduced engine performance, potential for aftertreatment system damage, and increased emissions. In diesel vehicles, failure of the EGT sensors can prevent proper DPF regeneration, eventually causing severe engine or DPF damage. Prompt inspection and repair are recommended.

Vehicles Most Commonly Affected by P20E2 #

P20E2 is most frequently encountered in modern diesel vehicles equipped with advanced emission control systems. The following vehicle types and OEMs are often reported to experience this code:

• Ford Super Duty Diesel (F-250, F-350, Transit)
• Volkswagen/Audi TDI models
• GM/Chevrolet Duramax Diesel pickups
• RAM Cummins Diesel trucks
• Mercedes-Benz BlueTEC diesels
• BMW diesel models

Common Mistakes & Best Practices for P20E2 #

Misdiagnosis is possible if shortcuts are taken or if sensor data is not thoroughly compared. To avoid unnecessary expenses and ensure a correct fix, consider the following:

• Don’t just replace the sensor based on the code alone. Always compare actual readings and check wiring.
• Don’t ignore potential exhaust leaks. They can cause false temperature readings.
• Don’t clear the code until the root cause is confirmed and repaired.
• Always check for OEM TSBs or software updates. Some issues may be known to the manufacturer.
• Document pre- and post-repair sensor readings. This helps confirm a successful repair.

Quick FAQ: P20E2 #

Here are quick answers to common questions about DTC P20E2:

• Q: Will P20E2 cause my vehicle to fail an emissions test?
  A: Yes, if the Check Engine Light is on and the code is active, your vehicle will not pass most OBD-II emissions inspections.
• Q: Can I reset the code and keep driving?
  A: Resetting the code without fixing the cause will only temporarily clear the warning. The code will return if the underlying issue is not addressed.
• Q: Are both sensors always bad if this code sets?
  A: Not necessarily. The code indicates a correlation fault, but often only one sensor or a wiring issue is at fault. Test each sensor independently.