OBD-II code · Powertrain (generic, extended)
P2688 Fuel Supply Heater Control Circuit Low
Voltage on the fuel supply heater control line is below the expected window. 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 P2688?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyControl wire shorted to ground
- PossibleRelay coil short
- Less likelyConnector pins corroded - high contact resistance
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Fuel Supply Heater, Wiring Harness
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.