P20E2 — Exhaust Gas Temperature Sensor 1/2 Correlation Bank 1

Causes

• Faulty EGT sensor (Sensor 1 or Sensor 2)
• Damaged wiring or poor connector/terminal connection between sensor(s) and ECM
• Exhaust leak between the two sensors or at nearby joints
• Sensor contamination (soot, oil, molten DPF material) or physical damage
• Blocked/partially plugged DPF or exhaust restriction causing uneven temperatures
• Intermittent sensor heater failure (if sensors are heated)

Symptoms

• MIL/Check Engine Light illuminated with P20E2 stored
• Possible reduced engine power or limp mode depending on ECU strategy
• DPF regeneration inhibited or abnormal regeneration behavior
• Unusual exhaust smell or visible exhaust leaks
• Higher than normal fuel consumption or smoke during regeneration

What to check

• Read freeze-frame and live data with a scan tool: record both EGT sensor temperatures during key conditions (idle, wide open throttle, steady load, during regen)
• Visual inspection of EGT sensors, wiring harnesses, and connectors for damage, corrosion, or loose fittings
• Inspect exhaust system for leaks, cracked flanges, broken clamps, or damaged gaskets between sensors
• Compare response times: heat both sensors with load and observe if one lags or doesn't follow the other
• Check sensor heater circuit (if applicable) for proper voltage/current and continuity to ECM
• Measure sensor resistance/voltage output per manufacturer spec (or compare sensor outputs to each other)

Signal parameters

• Expected EGT operating range: typically up to 800–1,000 °C during regen (varies by vehicle — consult service manual)
• Typical correlation: under steady conditions the two sensors should track each other closely (delta usually < 30–50 °C; a delta > ~100 °C often triggers correlation faults — consult OEM threshold)
• Sensor output types vary by vehicle: thermocouple (mV output), NTC/resistive (ohms), or 0–5 V sensors — verify type before measuring
• Heater circuit (if present): nominal 12 V supply with rated current draw (often 0.5–3 A); an open heater will show no current
• If using voltage measurements, expect smooth, monotonic increase with temperature; noisy, flat, or pegged readings indicate a fault

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