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Home / DTC / P2051 — Reductant Injection Valve Circuit Low Bank 2 Unit 1

P2051 — Reductant Injection Valve Circuit Low Bank 2 Unit 1

Detailed page for trouble code P2051.

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P2051

Generic P — Powertrain

Reductant Injection Valve Circuit Low Bank 2 Unit 1

Brand: Generic
Type: P — Powertrain
Views: UK: 12 EN: 21 RU: 17
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Page language: EN

Causes

  • Short to ground in reductant injector control wiring
  • Open or high-resistance wiring/connector to reductant injector
  • Corroded/loose connector or pin damage at valve harness
  • Failed reductant injection valve (solenoid)
  • Blown fuse or faulty relay supplying injector power
  • Ground fault or poor ground connection

Symptoms

  • Malfunction Indicator Lamp (MIL) or DEF/aftertreatment warning lamp illuminated
  • Reduced or disabled reductant injection — may cause increased NOx emissions or failed emissions test
  • Aftertreatment system warnings, possible limp/derate mode
  • Active SCR regeneration disabled or limited
  • Possible diagnostic trouble codes stored for related systems (NOx sensor, SCR)
  • Possible DEF/urea system messages (low flow, injector fault)

What to check

  • Read freeze frame and freeze data; note engine conditions when code set
  • Retrieve all related DTCs (NOx sensors, other SCR injector codes, power/ground faults)
  • Visual inspection of Bank 2 reductant injector connector, wiring loom, and chassis ground points for damage, corrosion, or rubbing
  • Check fuse(s) and relay(s) feeding the reductant injection circuit
  • Back-probe injector connector with ignition ON and with injector commanded ON while monitoring voltage/current
  • Measure injector coil resistance with connector disconnected and compare to manufacturer spec

Signal parameters

  • Supply voltage (key ON, engine OFF) at injector feed: ~battery voltage (vehicle specific)
  • Control signal behavior: many systems switch ground to activate injector; when inactive the control line may be near battery voltage; when active it is pulled low (~0 V) — behaviour is manufacturer dependent
  • Typical solenoid coil resistance (generic): roughly 2–30 ohms (vehicle-specific — consult manufacturer spec)
  • Expected current when activated: commonly 0.3–2.0 A (vehicle-specific)
  • A low-voltage fault means the ECM measured an unexpectedly low voltage on the control/supply circuit (often indicating a short to ground)

Diagnostic algorithm

  1. Confirm vehicle specifics and ECM wiring diagram for Bank 2 Unit 1 reductant injector to know supply, control strategy (ground- or power-switched) and fuse/relay locations.
  2. Scan for DTCs and record freeze frame/live data. Note whether injector was being commanded and any correlated NOx sensor data.
  3. Visually inspect the injector, connector, wiring harness, and ground points for damage, corrosion, pin push-out, or water ingress.
  4. With ignition ON (engine OFF), measure supply voltage at the injector power pin and control pin. Compare to battery voltage and expected idle values from wiring diagram.
  5. Disconnect connector and measure injector coil resistance with a DMM; compare to spec. Very low resistance suggests shorted coil; infinite/open suggests open circuit.
  6. Back-probe the control pin and command the injector ON via a scan tool while observing voltage and current. Note if the control line is being driven correctly (switches to ground or to +12 V as specified) and if current draw is within expected range.
  7. If the control line is low with the injector disconnected, inspect wiring for shorts to ground between connector and ECM. Perform continuity checks from harness pin to chassis ground and to ECM pin.
  8. Perform a wiggle test of harness while monitoring live data to find intermittent faults. Repair any chafing or damaged sections.
  9. Replace or bench test the injector if coil resistance/current draw is out of range. If injector bench test is good and wiring checks out, suspect ECM driver damage and consult manufacturer guidance for ECM testing/replacement.
  10. After repair, clear codes, perform active tests if available, and verify proper operation with a test drive and re-scan for stored codes.

Likely causes

  • Wiring shorted to chassis ground at or near Bank 2 injector connector
  • Connector corrosion allowing loss of voltage or intermittent low reading
  • Internal failure of the reductant injection valve coil (low or shorted winding)
  • Failed power supply fuse/relay for reductant injector circuit
  • ECM output stage damaged (less likely than wiring/valve issues)

Fault status

⚠️ Status
MIL illuminated — Reductant injection valve circuit low detected for Bank 2 Unit 1. Aftertreatment/DEF system warning may be present.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5 - 3.0 hours

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P2050 P2052 P2053 P2060 P20A0
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