P2477 code meaning
Exhaust Gas Temperature Sensor Circuit Intermittent/Erratic (Bank 2 Sensor 4)
Powertrain system Generic code P24xx codes Check engine light
What P2477 means
P2477 targets a signal from bank 2 probe 4 that jumps around, while each individual sample may still be in range. Real exhaust temperature changes only gradually because the probe and pipe have thermal mass, so sudden steps between consecutive readings betray a wiring or contact issue. GM documents the method for the bank 1 sibling P2472: its 2017 diesel table counts samples with a resistance step above 10 ohms and fails at 15 of 30, as a Type B fault with the MIL on the second trip. P2477 itself appears in no public maker document. Faults tend to come and go with vibration or heat, so wiggling the harness while watching live data is the usual way to find them.
P2477 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 P2477
- MIL on after the second faulty trip
- Value of bank 2 probe 4 jumps in live data
- Fault code returns after being cleared
Common causes of P2477
- Most likelyLoose or corroded pins in the probe connector
- PossibleWire strands breaking near the hot pipe
- Less likelyCracked probe element with unstable contact
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Egt sensor b2s4Egt wiring
What each part of P2477 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). |
| 77 | The exact fault in that area. |
What to do next
- Note P2477 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 P2477
What does P2477 mean?
P2477 means "Exhaust Gas Temperature Sensor Circuit Intermittent/Erratic (Bank 2 Sensor 4)". P2477 targets a signal from bank 2 probe 4 that jumps around, while each individual sample may still be in range. It is a generic code, so it means the same on every make.
Is it safe to drive with P2477?
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 P2477 fail an emissions test?
Yes, it can. P2477 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 P2477 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 P2477 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.