What does it mean?
B1825 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Trunk Release Switch Input Circuit/Performance .
Symptoms
- Trunk release button no longer opens the trunk
- Trunk unlocks by itself or the actuator buzzes with nobody at the car
- Remote trunk release also stops working
- Battery drain because the release solenoid stays energised
- No sound at all from the release actuator when the button is pressed
Likely causes
- Trunk release switch contacts worn or stuck pressed
- Water reaching the switch, whether it sits in the trunk lid, the dash or the door sill
- Open or short in the switch signal wire
- High-resistance or missing ground for the release switch
- Module measuring an implausibly long press, which it treats as a stuck switch
- Broken conductor in the flexible loom between the body and the trunk lid
- Aftermarket release button wired into the same circuit
How to fix it
- Check the trunk release switch status in live data with the button untouched
- Unplug the switch and see whether the input clears
- Measure the contact resistance pressed and released
- Inspect the switch area and trunk lid loom for water and corrosion
- Check the fuse feeding the release circuit and the switch ground
- Repair the signal wire or replace the switch
- Retest the release function and confirm the code does not return after several cycles