P05C3Engine Coolant Pressure Sensor Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Needs a drive cycle to confirm a fix
- How the car detects it
- An engine coolant pressure sensor (5 V reference, ratiometric signal) measures pressure in the cooling circuit; in a sealed circuit pressure rises with temperature, so deviations reveal leaks or a loose cap – described in Navistar and GE patents for commercial and rail engines. No manufacturer document available to us uses P05C2–P05C6 for passenger cars; CARB requires input components to be checked for circuit faults, range and plausibility. P05C3 means the signal is valid but implausible – for example not near ambient pressure with a cold, equalised circuit, or not following temperature during warm-up. A real pressure loss from a leak or faulty cap can also land here.
- What you may notice
- Check engine light or warning (depending on the maker)
- Coolant loss or smell with a real leak
- Possibly rising temperature
- Likely causes
- LikelySensor drifting or stuck (fouled pressure port, scale)
- PossibleReal pressure fault: leak, faulty radiator or expansion tank cap
- PossibleAir in the cooling system after filling
- RareCombustion gas in the coolant (head gasket)
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.