P2146 — Injector Group “A” Supply Voltage Circuit/Open

Category

Powertrain → Fuel System (Electronic Injector Control)

What it means (plain English)

Your ECM powers the injectors in groups (often “A” and “B”) through a common supply circuit. A P2146 code means the ECM has detected an open or missing voltage in the Group “A” injector supply circuit.

Instead of just one injector failing (like P0201–P0208), this affects multiple injectors at once — typically cylinders 1, 2, 3 (depending on the engine platform).

Symptoms

  • MIL (Check Engine Light) illuminated
  • Hard starting or no-start (if multiple injectors can’t fire)
  • Rough idle and misfires
  • Loss of power, derate/limp mode possible
  • White/black smoke from incomplete combustion
  • Poor fuel economy

Priority Level

Very High —
If the ECM loses power supply to a full injector group, the engine will run extremely rough or may not start at all. This can lead to breakdowns and unsafe drivability.

Common Causes

  • Open circuit in injector Group “A” power harness
  • Chafed, pinched, or rubbed-through injector wiring near valve cover or engine block
  • Corroded injector connector or ECM pins
  • Failed injector driver circuit inside ECM
  • Poor battery or ground connections
  • Water/oil contamination in harness

How Pros Diagnose It (step-by-step)

  1. Scan tool check — confirm P2146 and note if companion injector codes (P020x) are present.
  2. Visual inspection — look for harness rub-through near fuel rail, valve cover, or under intake.
  3. Check power supply to injector Group “A” with a test light or multimeter (KOEO and cranking).
  4. Continuity test wiring from ECM to injector harness.
  5. Connector inspection — corrosion, bent pins, oil intrusion.
  6. Load test — ECM may supply voltage at rest but drop out under load if driver circuit is failing.
  7. If wiring and connectors check out, suspect ECM injector driver failure.

Likely Fixes

  • Repair/replace damaged wiring harness (common near valve cover)
  • Clean or replace corroded connectors
  • Replace failed injectors if shorted and pulling down circuit
  • Replace ECM/PCM if internal injector driver circuit is bad
  • Verify and repair poor battery/ground connections

Related/Companion Codes

  • P2147 — Injector Group “A” Supply Voltage Circuit Low
  • P2148 — Injector Group “A” Supply Voltage Circuit High
  • P2150–P2155 — Injector Group “B” Circuit faults
  • P0201–P0208 — Individual injector circuit codes

Tech Notes (Quick Hits)

  • Cummins ISX/ISB — harness rub-through near intake manifold is a top culprit.
  • GM Duramax (LMM/LML) — connector corrosion at the valve cover injector harness often causes this.
  • If multiple injectors on one bank stop firing, suspect the group supply circuit before condemning all injectors.
  • Many OEMs recommend checking for Technical Service Bulletins (TSBs) — some ECMs had known injector driver issues.

Severity: Very High — Repair Immediately
A P2146 code means your truck has lost supply voltage to a group of injectors. This often causes rough running, no-start conditions, or severe power loss. Quick repair of wiring, connectors, or the ECM is essential to get the engine running reliably again.

🔗 Sources & References: