P04BA: Fuel Fill Door Position Sensor Circuit High

What it means

Same as P04B8 with the signal voltage above the plausible range. 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.

How it works

The fuel-fill door position switch sends a signal voltage to indicate whether the door is open or closed. The control module monitors that signal and sets P04BA when it rises above the plausible range. A signal wire shorted to supply or a poor connector connection can hold the reading high.

Common causes

Most likely first.

1. Signal shorted to supply
2. Connector pins corroded - high contact resistance
3. Supply wire pinched against B+ source

Symptoms

• Fuel-fill door status may be unavailable or incorrect
• Door may not release or lock as expected

How to diagnose it

1. Check live fuel-door position data and confirm that the signal is high while comparing it with the actual door position.
2. Inspect the switch connector and harness for corrosion, pushed-back pins, pinched wiring, or contact with a power source.
3. With live data displayed, gently move the harness and connector to see whether the high reading changes.
4. Measure the signal circuit and check for a short to supply, following the manufacturer's specification.
5. If the wiring checks out, test the position switch and its supply and ground before deciding which component has failed.

Common fixes

• Repair a pinched or damaged signal wire that is shorted to supply.
• Clean and repair corroded connector terminals or secure a pushed-back pin.
• Replace the position switch if it produces a high signal despite sound wiring and correct supply and ground.

Can I keep driving?

Driving is usually safe, but fuel-door status may be incorrect and the door's release or lock operation may be affected. Check that the door is latched before driving and avoid relying on the status display until repaired.