Powertrain, generic (extended)

P201A Reductant Injection Valve Circuit Range/Performance (Bank 2 Unit 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Bank 2 dosing valve sticking from urea crystals or deposits
Corroded connector or harness adding resistance to the valve circuit
DEF pressure at the valve outside the expected range

Symptoms

  • Malfunction indicator lamp on
  • DEF system warning, possibly countdown to speed limitation

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant injection valvereductant metering unitscr catalyst

Related codes

P202EP2050P208FP205F

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.