OBD-II code · Body
B0420 Audio System Internal Failure
The audio head unit reports an internal self-test failure. Symptoms include silent output, frozen display, or repeated reboots of the infotainment system.
Is it safe to drive with B0420?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHead unit internal fault
- PossibleSoftware update required
Symptoms
- Warning light or symbol related to the affected system
- Comfort or safety function impaired
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Usually unaffected
- Parts involved
- Audio Head Unit, Infotainment Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.