U0604Lost Communication With Fuel Pressure Sensor B
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Sensor B is the second fuel pressure measuring point, for example a low-pressure sensor in the feed line of a direct injection engine or a second rail on V engines; which pressure it reads depends on the maker. U0604 flags that this digital sensor has stopped sending valid SENT frames to the engine controller. Nobody publishes a manufacturer description for this code. By analogy with Ford's SENT checks for oil and filter pressure sensors, the controller would look for driver errors, a line held high or low or missing frames and confirm after a few seconds. CARB 1968.2 requires separate lost-communication codes for coded digital inputs. P018A is the analog circuit code for sensor B, U0603 the counterpart for sensor A. Depending on the role, pump control or the second rail falls back to defaults.
- What you may notice
- Check engine light on
- Hesitation or reduced power under load
- Likely causes
- LikelyDamaged signal, supply or ground wire to sensor B
- PossibleSensor B failed internally
- RareSensor A and B connectors swapped or loose
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.