OBD-II code · Powertrain (generic, extended)
P2051 Reductant Injection Valve Circuit Low (Bank 2 Unit 1)
Reductant Injection Valve Circuit Low (Bank 2 Unit 1): the signal voltage is below the expected range. This valve doses reductant (DEF/AdBlue) into the exhaust for SCR NOx reduction.
Is it safe to drive with P2051?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyShort to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.7–3 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Injection Valve
Related codes
- P2048Reductant Injection Valve Circuit Low (Bank 1 Unit 1)
- P2054Reductant Injection Valve Circuit Low (Bank 1 Unit 2)
- P2057Reductant Injection Valve Circuit Low (Bank 2 Unit 2)
- P204EReductant Pressure Sensor Circuit Intermittent/Erratic
- P204FReductant System Performance
- P2050Reductant Injection Valve Circuit/Open (Bank 2 Unit 1)
- P2052Reductant Injection Valve Circuit High (Bank 2 Unit 1)
- P2053Reductant Injection Valve Circuit/Open (Bank 1 Unit 2)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.