OBD-II code · Powertrain (generic)
P04D4 Exhaust Brake Input Circuit Range or Performance
Same as P04D3 with the signal in plausible range yet not matching expected behaviour - e.g. activation request without driver input or no response after a request.
Is it safe to drive with P04D4?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySignal implausible against driver action or bus
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.6–1.8 h
- Emissions test
- Usually unaffected
- Parts involved
- Exhaust Brake Request Switch
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.