P04D7
Exhaust Brake Input Circuit Intermittent or Erratic
Same as P04D3 with intermittent or erratic signal. The exhaust control valve modulates exhaust backpressure or routing (EGR feed, sound, regen support); a malfunction shifts torque mapping and may trigger limp mode.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Intermittent contact at connectorCommon
- Connector with intermittent contact under vibrationLess likely
- Harness routed against vibrating componentLess likely
Parts involved
- Exhaust Brake Request Switch
- Exhaust Brake Wiring
P04D7 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.