P23A0

Fuel Injector Group A Supply Voltage Circuit/Open

P23A0 is a generic OBD-II powertrain diagnostic trouble code: Fuel Injector Group A Supply Voltage Circuit/Open. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P23A0
Group
Powertrain
System
Powertrain
Severity
Critical (limp mode / no-start)
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What P23A0 means

P23A0 is set when the ECM detects that the supply voltage to the fuel injector group A circuit is absent, below threshold, or that there is an open in the injector supply rail for that group. Modern engines with multiple injector groups or bank-fired systems monitor the high-side voltage feed to each bank of injectors; a loss of supply on group A means one or more injectors will not receive the power they need to operate, resulting in misfires or a complete no-start condition.

Injector supply circuits are typically protected by a dedicated fuse or relay. A blown fuse is often the simplest and first item to check. If the fuse is intact, a failed injector driver relay, an open or high-resistance wiring path between the fuse/relay and the injector connectors, or a shorted injector internally dragging down the supply rail can all produce this code.

The severity depends on how many cylinders are served by group A. If all cylinders share group A, a no-start or immediate engine shutdown results. If group A is a subset, partial power loss occurs. Note that a shorted injector may repeatedly blow the supply fuse; check for a short before installing a new fuse to avoid repeated failure.

Common causes

Most-frequently reported root causes when P23A0 is logged.

  • 1
    Blown fuse in the injector group A supply circuit.
  • 2
    Failed injector supply relay for group A.
  • 3
    Open or broken wire in the injector group A supply voltage harness.
  • 4
    Corroded or loose connector at the injector supply feed or distribution point.
  • 5
    Internally shorted fuel injector loading down and collapsing the supply rail.
  • 6
    Damaged wiring harness caused by heat, vibration, or rodent damage.
  • 7
    ECM internal high-side driver fault for injector group A supply.

Symptoms drivers notice

Engine misfire on all cylinders in injector group A, or complete no-start.
MIL illuminated with multiple cylinder misfire codes accompanying P23A0.
Strong fuel smell if injectors are not receiving power but the pump continues to run.
Rough running limited to specific cylinders if only a subset is in group A.
Possible stall or inability to restart after the fault sets.

How to diagnose P23A0

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all DTCs and note which cylinders have companion misfire codes to identify the scope of group A.
  2. 2
    Locate and inspect the injector group A supply fuse; replace if blown and investigate the cause before re-energizing.
  3. 3
    Verify the injector supply relay for group A is energizing correctly with a scan tool or by listening for a click at key-on.
  4. 4
    Measure supply voltage at the injector group A harness connector with the ignition on.
  5. 5
    Inspect the supply wiring harness from fuse/relay to the injector connectors for opens, chafing, or corrosion.
  6. 6
    Disconnect injectors one at a time and check if the supply voltage returns; a shorted injector will restore voltage when unplugged.
  7. 7
    If wiring and components are intact, check the ECM injector supply driver output.

Related powertrain codes

Frequently asked questions

Will the car start with P23A0 active?

If group A covers all injectors, the engine will typically not start or will stall immediately; if group A is a subset, partial running may occur.

Can a shorted injector cause P23A0?

Yes. A shorted injector draws excessive current that can blow the supply fuse or pull the supply voltage low, triggering the circuit/open detection.

How do I find which injector is shorted?

Disconnect injectors one at a time with the circuit powered and watch for the supply voltage to recover; when it does, the last disconnected injector is the faulty one.

Is P23A0 ever caused by the ECM itself?

ECM driver failures are possible but uncommon; rule out all external wiring and component faults before suspecting the ECM.

Disabling P23A0 in software

RaceTune can permanently disable P23A0 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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