P053C
PCV Heater A Control Circuit High.
- Generic
- Powertrain
- Generic code
- Low severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 5
- AreaVehicle speed, idle control and auxiliary inputs
- 3C
- FaultThe specific fault in that area
What it means
P053C is the generic code for a high condition in the control circuit of PCV (positive crankcase ventilation) heater A. The heater stops moisture in the crankcase vent path freezing in cold weather. The engine control unit sets the code when it sees a voltage or current in the heater control circuit that is higher than expected for the commanded state.
Symptoms
- Engine warning light on
- Usually no change in how the car drives
- Possible rough idle or whistling if the crankcase vent path has frozen in cold weather
- Oil vapour or moisture residue around the breather hose or PCV valve
- Other PCV or heater circuit codes stored alongside it
Possible causes
- Short to voltage in the PCV heater control wiringlikely
- Faulty PCV heater element or integrated heater and valve assembly with an internal faultlikely
- Damaged, corroded or contaminated connector at the heater or control unitpossible
- Faulty heater relay or driver stuck on, where fitted (depends on model)possible
- Chafed or melted harness near hot engine componentspossible
- Internal fault in the engine control unit output driverrare
How to diagnose
- Read all stored codes and freeze frame data, noting engine temperature and ambient conditions when the code set
- Check for related PCV, heater or circuit voltage codes and for any manufacturer bulletins for the model and engine
- Visually inspect the PCV heater, breather hoses and harness for heat damage, chafing, oil contamination or loose fittings
- Disconnect the heater connector and inspect the terminals for corrosion, bent pins, moisture or oil ingress
- Measure the heater element resistance and compare it with the manufacturer specification for that engine
- With the connector disconnected, check the control wire for a short to voltage and the supply and earth feeds against the wiring diagram
- Check the heater relay and fuse if the circuit uses them, and confirm the control signal operates as commanded using a scan tool's active test if available
- Clear the code and road test, then recheck to see whether it returns
How to fix
- Repair or replace the wiring that is shorted to voltage, and secure it away from heat and sharp edges
- Replace the PCV heater or the valve assembly if the element or its internal circuit is faulty
- Clean or replace corroded or damaged connectors and terminals
- Replace a faulty heater relay if one is fitted
- Replace the control unit only after wiring, heater and supply have been proven good, and have it programmed as required
Can I keep driving?
Low severity
The car can normally be driven while you arrange a repair, as this is mainly an emissions-related circuit fault. In freezing weather a frozen vent path can cause pressure build-up and oil leaks, so get it checked soon.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.