Exhaust Gas Temperature Sensor 2/3 Correlation Bank 1
The P20E4 code indicates a correlation issue between exhaust gas temperature (EGT) sensors 2 and 3 on Bank 1. These sensors monitor exhaust temperature for diesel particulate filter (DPF) regeneration and emissions control. When their readings diverge beyond a threshold, the PCM sets this code, often due to sensor failure, wiring problems, or exhaust leaks.
1. Most Common Causes
- Faulty EGT sensor 2 or 3 (thermal drift, internal damage)
- Incorrect mounting position difference between the two sensors
- Excessive soot buildup on one of the sensors
- Exhaust gas leaks between the measurement points
- Damaged wiring, corroded connectors, or abnormal resistance in the circuit
- Mechanical issue in the aftertreatment system (clogged DPF, faulty SCR)
2. Symptoms You Will Notice
- Check Engine Light on
- Reduced fuel economy
- Possible DPF regeneration issues
- Decreased engine performance
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect EGT sensor 2 and 3 wiring and connectors for damage.
Step 3: Compare live data from both sensors; look for erratic or out-of-range values.
Step 4: Check for exhaust leaks near the sensors using a smoke machine.
Step 5: Test sensor resistance and voltage per manufacturer specs.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can lead to DPF damage and reduced performance. Short trips may be okay, but address promptly.
How much does it cost to fix?▼
Typically $50-$150 for a sensor replacement, plus diagnostic time. Total cost may be higher if wiring repairs are needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.