P05C5

Symptoms

• Check Engine Light Is On
• Pressure readings on the scanner are abnormally high or off the charts
• The engine may overheat if the thermostat is stuck
• The cooling system safety valve may trip
• Emergency mode of engine operation with power limitation

Causes

• Short circuit of the sensor signal wire to the reference voltage (+5V) or on-board network (+12V)
• Internal pressure sensor failure (signal fixed at maximum)
• Really high pressure in the cooling system (stuck thermostat, overheating)
• Faulty expansion tank cap (does not release excess pressure)
• Damage to wiring with short to power

How to Fix

1. Immediately check the engine temperature - if there are signs of overheating, turn off the engine and allow to cool
2. Connect a scanner and evaluate the coolant temperature and pressure readings in real time
3. At normal temperature: check the sensor signal wire for short to power
4. Check the reference voltage at the sensor connector (should be about 5V, no more)
5. Connect a pressure gauge to the cooling system and compare the actual pressure with the scanner readings
6. Replace the sensor if the pressure is normal and the signal is too high; check the thermostat and reservoir cap at really high pressure

Related codes

Error P05C5 by Vehicle Brand