OBD-II code · Powertrain (generic)
P040D EGR Temperature Sensor A Circuit High
EGR temperature sensor A above upper plausibility — open signal or short to B+. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
Is it safe to drive with P040D?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen signal line
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
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
- P041DEGR Temperature Sensor B Circuit High
- P04D1EGR Temperature Sensor C Circuit High
- P04E8EGR Temperature Sensor D Circuit High
- P040BEGR Temperature Sensor A Circuit Range/Performance
- P040CEGR Temperature Sensor A Circuit Low
- P040EEGR Temperature Sensor A Circuit Intermittent/Erratic
- P040FEGR Temperature Sensor A/B Correlation
- P0410Secondary Air Injection System Malfunction
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.