P2148 — Injector Group “A” Supply Voltage Circuit High

Category

Powertrain → Fuel System (Electronic Injector Control)

What it means (plain English)

This code sets when the ECM detects the voltage in the Group “A” injector supply circuit is higher than expected. This typically points to a short-to-voltage, regulator fault, or ECM driver error.

Symptoms

  • MIL on
  • Rough idle or misfire
  • Hard starting
  • Possible stalling or derate
  • May be intermittent depending on harness movement/heat

Priority Level

High —
Abnormally high voltage can damage injectors or the ECM if left unchecked.

Common Causes

  • Short-to-voltage in injector Group “A” wiring
  • Failed ECM driver circuit
  • Poor alternator/voltage regulator overcharging
  • Connector corrosion causing voltage spikes
  • Rare: faulty injector creating feedback

How Pros Diagnose It

  1. Scan tool check — confirm P2148 with freeze-frame data.
  2. Measure injector supply voltage with DVOM — compare to battery voltage.
  3. Inspect harness for shorts-to-power (especially near engine block).
  4. Check alternator output for overcharging condition.
  5. Substitute ECM or harness if persistent.

Likely Fixes

  • Repair/replace shorted wiring
  • Replace or repair alternator if overcharging
  • Replace ECM if driver circuit is stuck high
  • Replace damaged connectors

Related/Companion Codes

  • P2146 — Circuit/Open
  • P2147 — Circuit Low
  • P2150–P2155 — Group “B” faults
  • P0201–P0208 — Individual injector codes

Tech Notes

  • Cummins ISX/X15 often logs P2148 when alternator/regulator is overcharging the injector circuit.
  • Duramax: harness rub-through near the valve cover is a common short-to-voltage cause.

Severity: High — Repair Immediately
A P2148 code means injector Group “A” is receiving abnormally high voltage. This risks injector and ECM damage if not fixed quickly. Addressing wiring shorts or charging issues now prevents costly repairs.

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