P2150

Injector Group B Supply Voltage Circuit Low

P2150 is a generic OBD-II powertrain diagnostic trouble code: Injector Group B Supply Voltage Circuit Low. It is logged by the engine control unit when the fuel/inj monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P2150
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on, possible limp mode)
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What P2150 means

P2150 is set when the PCM detects that the supply voltage feeding injector group A is below the expected threshold. Modern direct injection and common-rail diesel systems use high-side driver circuits with dedicated supply lines; the PCM monitors these supply rails to confirm adequate voltage is available before commanding injector firing.

A low voltage on the group A supply circuit can prevent injectors in that group from firing correctly, leading to misfires, rough running, or complete cylinder dropout for the affected bank. The root cause is typically a wiring fault, a failed injector driver relay, or a supply circuit issue rather than a failed injector itself.

Because the supply circuit feeds multiple injectors simultaneously, a fault here can affect cylinder balance across an entire bank. Diagnosis requires identifying the supply circuit architecture for the specific vehicle, checking the relay or fuse feeding the injector group, and measuring voltage at the driver circuit under commanded conditions.

Common causes

Most-frequently reported root causes when P2150 is logged.

  • 1
    Open or high-resistance fuse or fusible link in the injector group A supply circuit.
  • 2
    Failed or intermittent injector driver relay for group A.
  • 3
    Wiring fault causing voltage drop on the supply line to group A injectors.
  • 4
    Short to ground on the group A supply rail pulling voltage below threshold.
  • 5
    PCM internal injector driver fault causing low supply feedback.
  • 6
    Corroded or loose connector at the injector group A supply point.
  • 7
    Battery or charging system voltage marginally low, exacerbating an existing circuit weakness.

Symptoms drivers notice

MIL illuminated with possible rough idle or misfires.
One or more cylinders in injector group A not contributing to power.
Engine may run but with reduced power or unstable idle.
Possible hard start if all group A injectors are affected.
Companion misfire codes (P030x) for the affected cylinders may be present.

How to diagnose P2150

A typical diagnostic flow when this code is present.

  1. 1
    Scan for all DTCs and note any companion misfire or injector circuit codes.
  2. 2
    Locate the injector group A supply circuit on a wiring diagram and identify the fuse and relay.
  3. 3
    Check supply voltage at the injector group A connector with ignition on and engine running.
  4. 4
    Inspect the relay and fuse for the group A supply circuit.
  5. 5
    Check for a short to ground on the supply wire with the injectors disconnected.
  6. 6
    Inspect connector terminals at the PCM driver circuit for corrosion or damage.
  7. 7
    Repair wiring or replace relay as indicated; verify all affected cylinders are firing after repair.

Related powertrain codes

Frequently asked questions

Does P2150 mean my injectors are bad?

Not necessarily. P2150 is a supply voltage fault for the injector group, which points to the power delivery circuit rather than the injectors themselves. Injector faults produce different codes.

How many cylinders are affected by group A?

The number and identity of cylinders in group A varies by manufacturer and engine configuration. A wiring diagram for the specific vehicle is needed to identify which cylinders belong to group A.

Can a weak battery cause P2150?

A battery or charging system that is significantly underperforming can pull supply voltages below threshold, particularly during cold starts when current demand is high. However, a dedicated circuit fault is more common.

Will the engine run with P2150?

Often yes, but with misfires, rough running, or reduced power. Complete no-start is possible if the supply fault is severe enough to prevent all group A injectors from firing.

Disabling P2150 in software

RaceTune can permanently disable P2150 — 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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