OBD-II code · Powertrain (generic)
P00B3 Radiator Coolant Temperature Sensor Circuit Low
Radiator coolant temperature sensor signal voltage below expected range. The engine coolant temperature sensor feeds warm-up enrichment, fan control and closed-loop entry — a stuck-cold reading keeps the engine in open loop and rich forever.
Is it safe to drive with P00B3?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySignal wire shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Likely to fail
- Parts involved
- Radiator Coolant Temp Sensor, Sensor Wiring
Related codes
- P00B0Turbocharger/Supercharger Boost Control B Module Performance
- P00B1Radiator Coolant Temperature Sensor Circuit
- P00B2Radiator Coolant Temperature Sensor Circuit Range/Performance
- P00B4Radiator Coolant Temperature Sensor Circuit High
- P00B5Radiator Coolant Temperature Sensor Circuit Intermittent/Erratic
- P00B6Radiator Coolant Temperature/Engine Coolant Temperature Correlation
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.