P201AReductant Injection Valve Circuit Range/Performance (Bank 2 Unit 1)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Engines with two SCR paths give each a DEF dosing valve. P201A concerns the first valve on bank 2: the circuit is not open or shorted, but what the control unit sees while dosing does not fit the command. No manufacturer documents P201A publicly; the pickup and truck SCR systems in the public record use one valve and report this fault as P202E. Those show the method: GM's 6.6 L LML counts commanded against actual valve states and fails after more than ten mismatches within 80 injection events, while Hino found that some faults came from software misjudging DEF pressure at the valve. CARB requires reductant delivery to be monitored. On bank 2 the same culprits apply: a valve stuck by crystals, a connector with added resistance, or wrong pressure. Too little DEF raises NOx and may start the inducement warnings.
- What you may notice
- Malfunction indicator lamp on
- DEF system warning, possibly countdown to speed limitation
- Likely causes
- LikelyBank 2 dosing valve sticking from urea crystals or deposits
- PossibleCorroded connector or harness adding resistance to the valve circuit
- RareDEF pressure at the valve outside the expected range
- 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: €100 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.