Check Engine Lamp Circuit
2000-2000 Audi A6 2.7L Turbo V6
The 2000 Audi A6 is equipped with a 2.7L V6 turbocharged gasoline engine. Below you'll find detailed b0420 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.
Description
Malfunction in the check engine/MIL indicator lamp circuit in the instrument cluster.
Symptoms
- Check engine light does not illuminate during bulb check
- Light stays on with no DTC stored
- Light flickering
- Cannot determine if engine codes are present
Common Causes
- Burnt out MIL bulb/LED
- Cluster circuit board fault
- Wiring from PCM to cluster damaged
- PCM MIL driver failure
Diagnostic Steps
- Check bulb during key-on bulb check
- Test MIL drive circuit from PCM
- Inspect cluster wiring
- Scan PCM for codes
- Test cluster LED
Repair Notes
Replace MIL bulb/LED in cluster or repair wiring from PCM to cluster.
Related Codes
Other Body Codes
- B0001Driver Frontal Stage 1 Deployment Control
- B0002Driver Frontal Stage 2 Deployment Control
- B0003Passenger Frontal Stage 1 Deployment Control
- B0004Passenger Frontal Stage 2 Deployment Control
- B0005Driver Knee Airbag Deployment Circuit
- B0006Passenger Knee Airbag Deployment Circuit
- B0010Driver Side Airbag Deployment
- B0011Driver Side Airbag Deployment Circuit Open
- B0012Driver Side Airbag Deployment Circuit Short to Ground
- B0013Driver Side Airbag Deployment Circuit Short to Battery
B0420 on Other Vehicles
Common Questions
What does code B0420 mean on a 2000-2000 Audi A6?
B0420 stands for "Check Engine Lamp Circuit". Malfunction in the check engine/MIL indicator lamp circuit in the instrument cluster.
What are the symptoms of B0420 on a Audi A6?
Common symptoms of B0420 include: Check engine light does not illuminate during bulb check, Light stays on with no DTC stored, Light flickering, Cannot determine if engine codes are present.
What causes B0420 on a 2000-2000 Audi A6?
Common causes of B0420 include: Burnt out MIL bulb/LED, Cluster circuit board fault, Wiring from PCM to cluster damaged, PCM MIL driver failure.
Last updated: March 2026