What does it mean?
P1663 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Change Oil Lamp Control Circuit Malfunction .
Symptoms
- The change oil / service lamp never lights, or stays on permanently after the oil life is reset
- The oil life reset procedure appears to do nothing
- MIL on with no change in how the engine runs
- Other cluster indicators may be affected at the same time
- The driver misses oil change reminders, which can lead to overdue service intervals
Likely causes
- Change oil indicator bulb or LED failed or removed
- Open or shorted control wire between the control module and the cluster
- Corroded or bent terminals at the cluster connector
- Internal failure of the cluster indicator circuit
- Failed output driver in the control module
- Blown instrument panel fuse
- A replacement cluster that does not match the vehicle configuration
How to fix it
- Confirm the lamp behaviour during the ignition-on bulb check before diagnosing anything else
- Carry out the oil life reset procedure and watch how the lamp responds
- Check the instrument panel fuse and the cluster power and ground feeds
- Unplug the cluster connector and inspect for corrosion, bent pins and weak terminal tension
- Measure continuity of the lamp control wire between module and cluster and test for shorts to ground and battery voltage
- Replace a burnt bulb or repair the cluster circuit board; verify the fitted cluster matches the vehicle if it was ever changed
- Do not confuse this indicator with a genuine low oil pressure warning; check actual oil level and pressure before dismissing the lamp