What does it mean?
P1911 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Reverse lamp circuit .
Symptoms
- Reverse lamps stay off, stay on with the selector in another position, or flicker
- Fuse for the rear lighting blows again shortly after replacement
- Warning message about the rear lighting and the malfunction indicator lamp on some vehicles
- Other rear lamps behave oddly if the shared ground is corroded
- Dark rear-view camera image and poor visibility when reversing
- Fault appears or worsens after rain or a car wash
Likely causes
- Short to ground in the reverse lamp wiring, often at the tailgate hinge flex point
- Water inside the rear lamp housing corroding the socket and bridging contacts
- Incorrect bulbs or non-approved LED bulbs upsetting the module's load monitoring
- Blown fuse, sometimes repeatedly, pointing to a short in the circuit
- Corroded or broken shared ground for the rear lamp cluster
- Range switch reporting Reverse incorrectly or intermittently
- Failed output driver in the control module
How to fix it
- Check which bulbs are fitted and confirm they match the specified type and wattage
- Open the lamp housing and inspect for moisture, green corrosion and a melted socket
- Check the fuse; with the lamps unplugged, test the circuit for a short to ground
- Confirm in live data that the range switch reports Reverse only when the lever is in R
- Clean and re-torque the rear lamp ground point and check it with a voltage-drop test
- Flex the tailgate or hinge harness while watching the lamps and repair any broken or shorted conductor
- Replace the lamp assembly or socket where it is damaged; replace the module only as a last resort