P25DA: Fuel Level Sensor C Circuit High

What it means

The Fuel Level Sensor C circuit signal is above the expected threshold. This identifies a high circuit condition but does not prove the sender is open or the signal is shorted to a particular reference.

At a glance

• Usually lights the check-engine light

How it works

Fuel Level Sensor C provides an electrical signal used to estimate how much fuel remains. P25DA sets when that signal is above its expected threshold; an open sender, a signal wire shorted to a reference supply, or a poor connection may cause it.

Common causes

Most likely first.

1. Open sender resistor
2. Signal wire shorted to the 5 V reference
3. Connector pins corroded - high contact resistance

Symptoms

• Fuel gauge may read inaccurately or at an extreme
• Fuel level warning may appear at the wrong time

How to diagnose it

1. Save freeze-frame data and compare the scan-tool Fuel Level Sensor C reading with the dashboard gauge and known fuel level.
2. Inspect the tank-module connector and accessible harness for loose or corroded terminals and wiring damaged near the tank.
3. Check connector contact condition, since corrosion or a weak connection can raise or distort the signal.
4. Use the manufacturer's procedure to test the signal wire for an open or short to the reference supply.
5. If wiring and connections pass, check the sender for an open resistor path and verify the control-module input using the manufacturer's procedure.

Common fixes

• Repair or reconnect a loose or corroded tank-module connector.
• Repair a signal wire shorted to the reference supply.
• Replace the sender if testing confirms an open resistor path.
• Repair the control-module input circuit only if testing confirms the fault is there.

Can I keep driving?

The vehicle may drive normally, but the gauge can read at an extreme and the low-fuel warning may be wrong. Refuel early and use mileage or another reliable method to track fuel until the signal is restored.