OBD-II fault code

P2157: Fuel Injector Group D Supply Voltage Circuit High

What it means

The supply voltage on injector group D is above the upper limit. Overvoltage on the group-D supply can mis-time or damage the injectors. Causes: charging-system overvoltage, a stuck supply relay or regulator, or a wiring fault shorting the group-D supply to a higher voltage.

At a glance

  • Usually lights the check-engine light
  • Affects emissions; the car can fail an emissions test

How it works

Injector group D receives power from a shared supply circuit, and the engine control module switches each injector to deliver fuel. This code sets when the module detects group D supply voltage above its expected upper limit, which may disrupt injector operation or damage components.

Common causes

Most likely first.

  1. Short to voltage in the injector supply circuit
  2. Charging system overvoltage
  3. Failed supply relay

Symptoms

  • Check engine light on
  • Misfire or rough idle on the affected cylinder
  • Increased fuel consumption
  • Possible fuel smell or smoke from exhaust

How to diagnose it

  1. Record freeze-frame data and check live misfire counts to determine when the group D high-voltage fault occurs and which cylinders are affected.
  2. Inspect the group D supply wiring and connectors for a short to a higher-voltage circuit, pinched insulation, or damaged terminals.
  3. Measure charging-system voltage under the conditions in the freeze-frame data and compare it with the manufacturer's specification.
  4. Measure voltage on the group D supply and compare it with the manufacturer's specification to confirm the high reading.
  5. If charging voltage is normal, test the group D supply relay and trace the circuit for a short to voltage.

Common fixes

  • Repair a group D supply wire shorted to a higher-voltage source.
  • Clean or replace damaged group D connector terminals.
  • Replace a failed or stuck injector supply relay.
  • Repair the charging system if its output exceeds the manufacturer's specification.

Can I keep driving?

Limit driving if the engine misfires or runs roughly, since prolonged misfiring can damage the catalytic converter; overvoltage can also harm electrical components. Stop if smoke or a strong fuel smell appears.

A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together

This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.

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