Powertrain, generic (extended)

P2051 Reductant Injection Valve Circuit Low (Bank 2 Unit 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2051 reports a ground fault on the drive wire of the DEF injector assigned to Bank 2, unit 1. Like its siblings P2050 and P2052, it presupposes a twin-bank SCR system with a dedicated valve per exhaust branch, and no manufacturer publishes a calibration or bulletin for it. The comparable Bank 1 tests give an idea of the limits: GM's 6.6 L LML flags less than roughly 0.5 ohm to ground for 2 s, and Ford's 2023 diesel logic reacts to valve current above 1.6 A. Where the second branch's harness passes hot exhaust parts, damaged insulation is the first thing to inspect. CARB treats the valve as a monitored component; once the code sets, that branch stops dosing and its NOx conversion collapses.

Likely causes

Insulation melted or chafed near the Bank 2 exhaust
Shorted coil in the Bank 2 injector
DEF crystals in the connector creating a path to ground

Symptoms

  • MIL on
  • Dosing on Bank 2 switched off
  • Possible NOx efficiency code for Bank 2 later

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–900
Time0.5–3 h

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

Parts involved

reductant injection valve

Related codes

P2050P2052P2048P2057

References: law.cornell.edu, gsi.ext.gm.com, fordservicecontent.com.