P25B2: Fuel Level Sensor A or B Stuck

What it means

The control module detects that fuel-level sensor A or B is stuck but does not identify which one.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The fuel-level system uses sensor A, sensor B, or both to estimate the amount of fuel in the tank. P25B2 indicates that the module sees one of the sensors stuck but does not identify which one, so diagnosis must compare both sensor readings.

Common causes

Most likely first.

1. Fuel level sensor A float stuck or binding
2. Fuel level sensor B float stuck or binding
3. Faulty sensor or damaged wiring or connector

Symptoms

• Fuel gauge remains fixed or changes inaccurately
• Incorrect remaining-range estimate
• Check-engine light may come on

How to diagnose it

1. Record freeze-frame data and read live fuel-level data for sensors A and B, if available, to see whether one stays fixed.
2. Compare both readings with the gauge and a known change in fuel level, allowing for the vehicle’s normal update delay.
3. Inspect accessible connectors and wiring for both sensors for damage, corrosion, loose pins, or poor contact.
4. If one sensor is identified and access is required, inspect its float and arm for binding against the tank, baffle, or pump module.
5. Test each sensor and its circuit separately using the manufacturer's procedure to identify which signal fails to change as specified.

Common fixes

• Repair a loose, corroded, or damaged connector or wire at the affected sensor.
• Free the A or B float that is binding inside its tank section.
• Replace the sensor whose float or resistive track fails testing.
• Repair a damaged sensor arm or tank-module interference that prevents free movement.

Can I keep driving?

You can usually drive if the vehicle runs normally, but the fuel gauge and remaining-range estimate may be wrong until the affected sensor is identified. Refuel early and track mileage to reduce the chance of running out.