P20B2Reductant Heater Coolant Control Valve Performance/Stuck Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P20B2 is a functional fault of the coolant valve that heats the reductant system: the circuit is intact, but temperatures do not follow the commanded valve position, most often because coolant keeps flowing while the valve should be shut. Hino uses the code in its dosing control unit and covers it in tech tip TT-16-014 for 2011–2017 conventional and 2013–2017 cab-over trucks. Most valves returned under warranty showed no defect, and a wrong DEF tank temperature input can set P20B2 falsely. Hino therefore asks to sort out any stored P205B to P205D or U02A2 first and, with the engine cold, to confirm that tank, pump and coolant temperatures agree within 8 °C (14 °F). Confirming the fault takes a drive with full warm-up.
- What you may notice
- Malfunction indicator with no other SCR fault stored
- DEF tank temperature runs unusually high
- Possible engine power restriction if left unrepaired
- Likely causes
- LikelyWrong DEF tank or pump temperature input misleading the valve check
- PossibleCoolant valve mechanically stuck open (deposits, debris)
- RareValve test blocked by other stored SCR faults, valve wrongly condemned
- 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 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.