OBD-II code · Powertrain (generic, extended)
P240B EVAP System Leak Detection Pump Heater Control Circuit Low
Same as P240A with the control line shorted to ground. The sensor heater warms the element to operating temperature (~600 °C); without it the lambda sensor stays inactive in closed loop and the ECM cannot trim mixture.
Is it safe to drive with P240B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyControl line shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–1.8 h
- Emissions test
- Likely to fail
- Parts involved
- Evap Leak Detection Pump Heater
Related codes
- P2408Fuel Cap Sensor/Switch Circuit Range/Performance
- P2409Fuel Cap Sensor or Switch Circuit Range or Performance
- P240AEVAP System Leak Detection Pump Heater Control Circuit Open
- P240CEVAP System Leak Detection Pump Heater Control Circuit High
- P240DAlternative Fuel Low Pressure System Leak
- P240EAlternative Fuel High Pressure System Leak
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.