U0616Lost Communication With Engine Coolant Bypass Valve B
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Valve B is a second electronically controlled coolant valve, for example one that splits flow between the block and the head or toward a heater or oil cooler; which valve carries the letter B depends on the manufacturer. No manufacturer documents U0616 publicly. The code means the controller has stopped receiving valid replies from that valve over its digital link, while valve A may still answer, so the fault is likely in the branch of wiring, the connector or the electronics of valve B itself. Suppliers such as Hella and Rheinmetall build these valves with LIN, PWM or SENT interfaces and internal position feedback. CARB requires a monitoring plan for engines that regulate temperature with more than one flow control device. P0E7B to P0E7E cover the electrical circuit of valve B.
- What you may notice
- Warning lamp, often without a noticeable change in driving
- Unusual warm-up behaviour or coolant temperature swings
- Likely causes
- LikelyDamaged signal, supply or ground wire in the branch to valve B
- PossibleLoose, corroded or wet connector at valve B
- PossibleElectronics in valve B failed
- RareController software or configuration does not match the fitted valve
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.