OBD-II code · Powertrain (generic)
P0598 Thermostat Heater Control Circuit Low
Same as P0597 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 P0598?
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
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
- Map Thermostat Heater
Related codes
- P0595Cruise Control Servo Control Circuit Low
- P0596Cruise Control Servo Control Circuit High
- P0597Thermostat Heater Control Circuit Open
- P0599Thermostat Heater Control Circuit High
- P059AActive Grille Air Shutter A Position Sensor Circuit
- P059BActive Grille Air Shutter A Position Sensor Range or Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.