P20B2 code meaning
Reductant Heater Coolant Control Valve Performance/Stuck Open
Powertrain system Generic code P20xx codes Check engine light
What P20B2 means
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.
P20B2 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor1 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P20B2
- Malfunction indicator with no other SCR fault stored
- DEF tank temperature runs unusually high
- Possible engine power restriction if left unrepaired
Common causes of P20B2
- Most likelyWrong DEF tank or pump temperature input misleading the valve check
- PossibleCoolant valve mechanically stuck open (deposits, debris)
- Less likelyValve test blocked by other stored SCR faults, valve wrongly condemned
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant coolant valve
What each part of P20B2 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| B2 | The exact fault in that area. |
What to do next
- Note P20B2 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P20B2
What does P20B2 mean?
P20B2 means "Reductant Heater Coolant Control Valve Performance/Stuck Open". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P20B2?
Drive gently and only to a workshop. With P20B2 the car can go into limp mode (reduced power) to protect itself.
Will P20B2 fail an emissions test?
Yes, it can. P20B2 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P20B2 to fix?
Difficulty: medium. A typical repair takes 1 to 3 hours of work. This is a job for a workshop.
Will P20B2 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.