OBD-II code · Powertrain (generic)
P040B EGR Temperature Sensor A Circuit Range/Performance
EGR temperature sensor A reads in range but plausibility check fails — slow response or stuck reading.
Is it safe to drive with P040B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor drift
- Less likelySensor element aged beyond calibration window
- Less likelySensor mounting loose - signal damping
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- Parts involved
- Egr Temperature Sensor
Related codes
- P040AEGR Temperature Sensor A Circuit
- P041BEGR Temperature Sensor B Circuit Range/Performance
- P0408Exhaust Gas Recirculation Sensor "B" Circuit Low
- P0409Exhaust Gas Recirculation Sensor "B" Circuit High
- P040CEGR Temperature Sensor A Circuit Low
- P040DEGR Temperature Sensor A Circuit High
- P040EEGR Temperature Sensor A Circuit Intermittent/Erratic
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.