What it means
Same as P053A with the control line shorted to ground. 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 to reduce the chance that moisture will freeze and block it. The engine control module monitors the heater control circuit and sets P053B when that line is lower than expected, commonly because it is shorted to ground.
Common causes
Most likely first.
- Control line shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
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 see when the path A heater fault was detected and whether it occurs in cold conditions.
- Inspect the path A heater connector and harness for rubbed-through insulation, moisture, corrosion, pin damage, or contact with grounded metal.
- Using the wiring diagram, test the control line for a short to ground and check connector terminals for secure fit and corrosion.
- Check the heater element and circuit components using the manufacturer's procedure to make sure a component fault is not pulling the control line low.
- Repair the fault, clear the code, and verify the control circuit behaves normally when the heater is commanded on.
Common fixes
- Repair chafed control-line insulation or wiring shorted to ground.
- Clean or replace corroded or damaged heater connector terminals.
- Replace the path A PCV heater if it is confirmed to be causing the low circuit condition.
- Repair a confirmed control-side fault after the heater and harness test correctly.
Can I keep driving?
If the engine runs normally, a short drive may be manageable, but have the fault checked before cold-weather use. Without a working PCV heater, moisture can freeze in the ventilation path, raising crankcase pressure and risking oil 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.