P242CExhaust Gas Temperature Sensor Circuit Low (Bank 1 Sensor 3)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P242C means the signal of exhaust temperature sensor 3 on bank 1 sits below its valid range. What that says about the wiring depends on the sensor type. GM's 2020 diesel tables (20OBDG04) read a resistance under 158 Ω as a grounded circuit and need 10 bad samples in a window of 20 (Type B); on the 3.0 L LZO a digital thermocouple module reporting below -72.8 °C counts the same way, with 19 of 25 samples. Ford's 2023 diesels use a voltage floor of 0.10 V, VW's 2014 Touareg TDI 0.68 V. Deutz describes P242C-00 as a grounded signal on the probe behind the SCR catalyst. A harness chafed through near the hot exhaust or a crushed connector is the usual find. The ECM then works with a substitute value and normally holds back regeneration.
- What you may notice
- MIL on after the second faulty trip on GM
- Sensor 3 shows an implausibly low temperature in the scan tool
- Regeneration blocked, filter load rising
- Likely causes
- LikelySignal wire chafed and shorted to ground near the exhaust
- PossibleConnector damaged, wet or with pushed-back terminals
- PossibleSensor shorted internally
- 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: €40 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.