P242C code meaning
Exhaust Gas Temperature Sensor Circuit Low (Bank 1 Sensor 3)
Powertrain system Generic code P24xx codes Check engine light
What P242C means
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.
P242C at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P242C
- 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
Common causes of P242C
- Most likelySignal wire chafed and shorted to ground near the exhaust
- PossibleConnector damaged, wet or with pushed-back terminals
- PossibleSensor shorted internally
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Egt sensor b1s3
What each part of P242C means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 2C | The exact fault in that area. |
What to do next
- Note P242C and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P242C
What does P242C mean?
P242C means "Exhaust Gas Temperature Sensor Circuit Low (Bank 1 Sensor 3)". P242C means the signal of exhaust temperature sensor 3 on bank 1 sits below its valid range. It is a generic code, so it means the same on every make.
Is it safe to drive with P242C?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P242C fail an emissions test?
Yes, it can. P242C is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P242C to fix?
Difficulty: medium. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P242C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.