P242BExhaust Gas Temperature Sensor Circuit Range/Performance (Bank 1 Sensor 3)
- 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
- P242B flags a reading from exhaust temperature sensor 3 on bank 1 that is electrically fine but makes no physical sense. Most checks start from a cold soak: GM's 3.0 L LZO (25OBDG04B) waits for more than 10,800 s engine-off and then expects the probe to warm up enough, which exposes a probe that has slipped from the gas stream or is frozen at one value (Type B). Ford's 2023 diesels want every probe within 50 °C of the others after 6 h off; VW's 2014 Touareg TDI compares sensor 3 with four other temperatures (60 K) and with its model (100 K). Not every case is a part fault: Volvo and Mack traced P242B on 2015–2016 trucks to a miscalculated soak time and issued software, and Jaguar found the DPF probe of the AJ20-D4 diesel loose or out of place. Jumpy signals go to P242E.
- What you may notice
- MIL on, often together with P2080 or P2084
- No DEF dosing or parked regeneration refused
- DPF warning lamp on
- Likely causes
- LikelySensor loose or no longer reaching into the exhaust stream
- PossibleSensor drifted or stuck at one value
- PossibleECM software miscalculating soak time (Volvo/Mack 2015–2016, software update)
- RareSensors swapped or wrong part fitted after repair
- 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: €0 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.