Powertrain, generic (extended)

P2056 Reductant Injection Valve Circuit/Open (Bank 2 Unit 2)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2056 refers to the fourth possible DEF injector position: the second valve in the Bank 2 exhaust line. It requires both a twin-bank layout and two dosing points per bank, a combination hardly any production engine uses; no manufacturer publicly documents the code. Detection would resemble GM's open-load check for metering valve 2 in its 2025 table (P2053): driver status read every 100 ms, more than 11 V on board, 30 bad samples out of 60, Type A. CARB lists reductant system valves among the electrical components whose circuits the OBD system has to verify. Before condemning a part, confirm which physical injector the scan tool assigns to Bank 2, unit 2, because confusing banks and units is an easy way to replace the wrong valve.

Likely causes

Connector of the Bank 2 second injector unplugged or corroded
Broken wire in the Bank 2 dosing harness
Open injector coil

Symptoms

  • MIL on
  • Reduced NOx conversion on Bank 2

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

P2057P2058P2053P2050

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