P242E code meaning
Exhaust Gas Temperature Sensor Circuit Intermittent/Erratic (Bank 1 Sensor 3)
Powertrain system Generic code P24xx codes Check engine light
What P242E means
P242E is set when exhaust temperature sensor 3 on bank 1 jumps between two samples faster than real exhaust gas can change, even though each single value is inside the valid range. GM documents this as a quick-change monitor that runs every 100 ms. The 2020 diesel tables look at the resistance step between consecutive samples and fail after 15 of 30 samples; the 3.0 L LZO evaluates the raw temperature step only while the reading is between 140 and 1,070 °C and needs 12 bad samples out of 25. Both are Type B, so the MIL waits for a second faulty trip. Loose terminals, corroded pins and a harness weakened by heat are the usual triggers, though the sensor can also fail internally. CARB asks for such checks on all emission-related inputs. A steady but wrong reading falls under P242B.
P242E at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P242E
- MIL after the second faulty trip
- Sensor 3 value jumps in the scan tool live data
- Code comes and goes, often after rough roads or washing
Common causes of P242E
- Most likelyLoose or fretted terminal in the sensor connector
- PossibleHarness insulation damaged by exhaust heat, intermittent contact
- Less likelySensor element breaking up 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 P242E 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). |
| 2E | The exact fault in that area. |
What to do next
- Note P242E 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 P242E
What does P242E mean?
P242E means "Exhaust Gas Temperature Sensor Circuit Intermittent/Erratic (Bank 1 Sensor 3)". P242E is set when exhaust temperature sensor 3 on bank 1 jumps between two samples faster than real exhaust gas can change, even though each single value is inside the valid range. It is a generic code, so it means the same on every make.
Is it safe to drive with P242E?
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 P242E fail an emissions test?
Yes, it can. P242E 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 P242E to fix?
Difficulty: medium. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P242E clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.