P20E4Exhaust Gas Temperature Sensor 2/3 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
- P20E4 covers the pair around the particulate filter: sensor 2 at the filter inlet and sensor 3 at its outlet on bank 1 no longer agree. GM documents the code for the diesel in table 15OBDG04 (also 14OBDG04): after a soak of at least 28,800 s the start-up values of the filter upstream and downstream sensors are compared against a look-up limit, and a larger gap is a Type B fault. Because both sensors steer and protect filter regeneration, a biased one can lead to regenerations that run too cool or too hot. P20E2 covers the pair around the oxidation catalyst, while P2084 and P242B report range faults of a single sensor. The patent US7533519 uses the same inlet/outlet arrangement for its stuck-in-range test. Drivers usually see the MIL and may notice more frequent or aborted regenerations.
- What you may notice
- Malfunction indicator lamp on
- Regenerations aborted or happening more often
- Filter loading warning in some vehicles
- Likely causes
- LikelyFilter inlet or outlet temperature sensor aged by heat cycling
- PossibleHeat-damaged or corroded sensor connector or lead
- RareHeavy soot or ash deposits on a sensor tip slowing its response
- 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.