P20E2Exhaust Gas Temperature Sensor 1/2 Correlation (Bank 1)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P20E2 flags that bank 1 exhaust temperature sensors 1 and 2 disagree at a moment when both should show nearly the same value. Sensor 1 usually sits ahead of the oxidation catalyst and sensor 2 behind it. GM runs this check on the 6.6 L Duramax LML/LGH (table 15OBDG09) and on the diesel of table 15OBDG04: after at least 28,800 s (8 h) with the engine off, the two readings captured at start-up are compared, and a gap above a limit taken from a look-up table counts as a Type B fault, so the MIL lights after two failing trips. A sensor that is offset but still inside its valid voltage window passes the circuit checks P0544 and P2031–P2033 and is only caught here. Drivers rarely notice more than the lamp, although GM blocks some regeneration functions while this code is active.
- What you may notice
- Malfunction indicator lamp on, often with no change in driving
- Particulate filter regeneration delayed or blocked
- Code returns after a long parking period
- Likely causes
- LikelyExhaust temperature sensor 1 or 2 drifted or aged (offset reading)
- PossibleCorroded or loose connector adding resistance to one sensor signal
- RareSensors swapped or a non-matching replacement part installed
- RareEngine control software needing an update
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.