P05C5 Engine Coolant Pressure Sensor Circuit High

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. P05C5 means the signal voltage is above its limit – usually a signal shorted to 5 V or battery voltage or an open sensor ground, not excessive coolant pressure.

Likely causes

Symptoms

• Check engine light or warning (depending on the maker)
• Coolant pressure or leak warning unavailable
• Usually no change in driving

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, patents.google.com, patents.google.com.