P20E5 — Exhaust Gas Temperature Sensor 1/2 Correlation #

Note: The description for code P20E5 may vary depending on the vehicle manufacturer. Always refer to the OEM (Original Equipment Manufacturer) documentation for the most accurate definition.

• Exhaust Gas Temperature Sensor 1/2 Correlation (General)
• Exhaust Gas Temp Sensor 1 and 2 Out of Range (Ford, GM)
• Sensor 1/2 Correlation Error (Dodge/Chrysler)
• EGT Sensor 1,2 Correlation Fault (Mercedes-Benz)

Code P20E5 Overview #

P20E5 is a diagnostic trouble code (DTC) that indicates a correlation issue between Exhaust Gas Temperature Sensor 1 and Sensor 2. These sensors monitor exhaust temperatures upstream (before) and downstream (after) in the exhaust system, helping the engine control module (ECM) balance emissions and protect critical components. When their readings don’t match as expected under certain driving conditions, the ECM flags P20E5. This code commonly points to sensor performance issues, wiring problems, or rare internal ECM faults. While not always urgent, ignoring this DTC can lead to increased emissions and potential damage to exhaust aftertreatment systems over time.

Common Symptoms for Code P20E5 #

Drivers may notice a range of symptoms when P20E5 is present. Sometimes, the only indication is an illuminated Check Engine Light (MIL). In other situations, drivability issues may arise, especially if the sensors’ readings are far off. If your vehicle is equipped with advanced emissions controls, you might notice reduced power or regeneration interruptions.

• Check Engine Light illuminated
• Possible reduced engine performance (limp mode) in some vehicles
• Occasional regeneration failures on diesel particulate filter (DPF) systems
• Increased exhaust emissions (not always noticeable to driver)
• Rarely, unusual exhaust smells or heat from the tailpipe

Most Likely Causes for Code P20E5 #

This DTC usually points to a problem with the exhaust gas temperature sensors or their circuits, but other issues can trigger it. Here’s what technicians find most often, in order of frequency:

1. Defective Exhaust Gas Temperature Sensor 1 or 2 (open circuit, internal short, or drifted calibration)
2. Wiring or Connector Problems (corrosion, broken wires, poor pin connections)
3. Exhaust leaks near the sensor locations (altering temperature readings)
4. Sensor contamination (soot, oil, or coolant fouling the sensor tip)
5. Failed or updated ECM/PCM calibration (rare, but possible)

Step-by-Step Diagnostic Guide for Code P20E5 #

A thorough diagnosis ensures you repair the right issue the first time. Here’s how a professional technician approaches P20E5:

1. Verify the DTC using a scan tool; note freeze frame data and any related codes.
2. Visually inspect the exhaust gas temperature sensors and wiring harnesses for signs of damage, loose connectors, or corrosion.
3. Check live data from both sensors with the engine cold and warming up; look for unreasonable or mismatched readings.
4. Backprobe sensor circuits with a multimeter to check for proper voltage supply, ground, and signal continuity.
5. Perform a resistance test on both sensors when cold and hot, comparing to manufacturer specifications.
6. Inspect for exhaust leaks near the sensor mounting points that could cause false readings.
7. Clear the code and test drive, monitoring live data to see if the fault returns.
8. If all tests pass, consider ECM/PCM software updates or replacement as a last resort.

Potential Repairs for Code P20E5 #

Once the root cause is found, the right repair will restore proper function. Here’s what’s typically needed, linked to the causes above:

• Replace faulty exhaust gas temperature sensor(s)
• Repair or replace damaged wiring or connectors
• Seal or repair exhaust leaks near affected sensors
• Clean or replace contaminated sensors (if applicable)
• Update or reprogram ECM/PCM software (very rare)

Is It Safe to Drive with Code P20E5? #

Limited: In many cases, the vehicle remains drivable with code P20E5, especially if no other symptoms are present. However, prolonged operation may increase emissions and, on some diesel vehicles, may prevent DPF regeneration, leading to further issues. If you notice reduced power, flashing warning lights, or excessive exhaust smoke, seek service as soon as possible.

Vehicles Most Commonly Affected by Code P20E5 #

Code P20E5 is seen in a variety of modern vehicles equipped with advanced emissions systems—especially diesels. It’s most often reported by:

• Ford trucks and vans (Power Stroke diesel engines)
• Chevrolet and GMC (Duramax diesel engines)
• Ram trucks (Cummins diesel engines)
• Mercedes-Benz Sprinter vans
• Some Volkswagen and Audi diesel models

Common Mistakes and Best Practices for Code P20E5 #

Avoid wasted time and money by following these professional tips:

• Don’t replace sensors without testing—check wiring and connectors first.
• Don’t ignore exhaust leaks—they can skew sensor readings and trigger false codes.
• Always compare both sensor readings on scan tool data before condemning a sensor.
• Don’t overlook software updates—sometimes, an ECM reflash is required to resolve false sensor correlation faults.

P20E5 FAQ #

Have more questions about P20E5? Here are quick answers to the most common ones:

• Q: Can I just clear the code and keep driving?
  A: Clearing the code may turn off the light temporarily, but the root cause will likely return. Always diagnose before clearing.
• Q: Do both sensors need to be replaced at the same time?
  A: Not necessarily. Only the faulty sensor (or affected wiring) needs replacement, unless both show abnormal readings.