What it means
Same as P053A with the control line shorted to supply. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The path A PCV heater warms the crankcase ventilation route so moisture is less likely to freeze and block ventilation. The engine control module monitors its control circuit and sets P053C when the line is higher than expected, which can indicate a short to supply.
Common causes
Most likely first.
- Control line shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check-engine light on
- Possible rough idle or crankcase ventilation problems in cold weather
How to diagnose it
- Review freeze-frame data and related codes to identify when the path A heater circuit fault occurred and whether the heater was commanded on.
- Inspect the heater connector and harness for pinched insulation, damaged terminals, corrosion, or contact with a power source.
- Use the wiring diagram to check the control line for a short to supply and inspect connector pin fit before testing components.
- Test the path A heater and related circuit components according to the manufacturer's procedure to determine whether the high reading comes from the harness, heater, or control side.
- Repair the confirmed fault, clear the code, and verify the circuit responds correctly to a heater command.
Common fixes
- Repair wiring pinched or shorted to a supply wire or terminal.
- Repair corroded, loose, or damaged connector pins and secure the connector.
- Replace the path A PCV heater if it is confirmed to cause the high circuit reading.
- Repair a confirmed control-side fault after the heater and wiring have been checked.
Can I keep driving?
If the engine runs normally, you may be able to drive briefly, but arrange a repair before operating in freezing weather. A blocked PCV path can build crankcase pressure and cause oil seepage or leaks.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.