P026A

Fuel Injector Group A Supply Voltage Circuit

P026A is a generic OBD-II powertrain diagnostic trouble code: Fuel Injector Group A Supply Voltage Circuit. 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
P026A
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P026A means

P026A is stored when the PCM/ECM detects an abnormal voltage condition on the power supply circuit feeding injector group A. Modern engines divide injectors into banks or groups sharing a common high-side driver; when the monitored voltage on that rail falls outside expected limits during an injection event, the fault is set.

This code differs from individual injector circuit codes because it implicates the shared supply wire, fuse, relay, or driver stage rather than a single injector coil. All cylinders served by group A may be affected simultaneously, causing a pronounced misfire or rough running condition that worsens under load.

Diagnosis should begin with a visual inspection of the injector fuse and power relay, followed by voltage and resistance measurements at the group A supply connector before suspecting the PCM driver. Wiring chafing against hot or moving components is a common root cause.

Common causes

Most-frequently reported root causes when P026A is logged.

  • 1
    Open or short circuit in the injector group A power supply wire.
  • 2
    Blown fuse on the injector supply circuit.
  • 3
    Failed fuel injector relay providing voltage to group A.
  • 4
    High-resistance connection at the injector harness connector.
  • 5
    PCM internal injector driver failure for group A.
  • 6
    Corroded or damaged wiring harness near the intake or exhaust manifold.
  • 7
    Intermittent ground fault pulling the supply voltage low.

Symptoms drivers notice

MIL illuminated with P026A stored.
Rough idle or engine misfire on cylinders in group A.
Reduced engine power or limp-mode torque limiting.
Hard start or extended cranking time.
Increased fuel consumption due to compensatory fueling.

How to diagnose P026A

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool, retrieve all DTCs, and note any accompanying misfire or injector codes.
  2. 2
    Inspect the injector group A fuse and replace if blown; check for the root cause of the overcurrent.
  3. 3
    Check voltage at the group A injector supply connector with the key on; compare to battery voltage.
  4. 4
    Inspect the injector power relay for proper operation and replace if faulty.
  5. 5
    Perform a wiring harness inspection for chafing, corrosion, or open circuits between the fuse box and group A connectors.
  6. 6
    Measure resistance of each injector in group A and compare to specification.
  7. 7
    If wiring and injectors test good, perform a PCM driver output test and suspect PCM if the driver is inoperative.

Vehicles where we've handled P026A

Platforms in our catalogue with confirmed P026A coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

Can I drive with P026A?

Short distances may be possible, but misfires can damage the catalytic converter and the engine may enter limp mode; repair promptly.

Will clearing the code fix the problem?

No. The code will return immediately if the underlying electrical fault is still present.

Is P026A always a PCM failure?

No. Wiring, fuse, and relay faults are far more common; always check external circuits before suspecting the PCM.

Which cylinders are in group A?

Group assignment varies by manufacturer and engine; consult the vehicle-specific wiring diagram to identify which cylinders share the group A supply.

Disabling P026A in software

RaceTune can permanently disable P026A — 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.

ECUs with a P026A disable in our catalogue

Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.

  • Bosch EDC17C50 verified 1 software version

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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