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DTC codes / P21xx · Fuel and air metering / P2157

P2157Fuel Injector Group 'D' Supply Voltage Circuit High

P2157 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the supply circuit for fuel injector group 'D', which is a set of injectors grouped together by the manufacturer for control or diagnostic purposes. The PCM expects the supply voltage to be within a specific range, and a high reading suggests an open circuit, a short to voltage, or a faulty injector driver.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp).
  • Often no symptoms besides the warning light, especially if the injector group is not critical under current conditions.
  • Rough idle or misfire if the high voltage causes injectors in group 'D' to stop firing.
  • Reduced engine performance or power, particularly under load.
  • Poor fuel economy due to improper fuel delivery.
  • In some cases, the engine may stall or hesitate during acceleration.

Common causes, most likely first

  1. Open circuit in the supply voltage wire to the injector group 'D' (broken wire, corroded connector, or loose terminal).
  2. Short to voltage on the supply circuit, possibly from chafed wiring contacting a power source.
  3. Faulty fuel injector in group 'D' with an internal open coil or high resistance.
  4. Poor electrical connection at the injector group 'D' harness connector or at the PCM connector.
  5. Defective PCM driver for the injector group 'D' supply voltage.
  6. Corrosion or water intrusion in the wiring harness or connectors.
  7. Aftermarket accessories or improper wiring repairs that interfere with the injector circuit.

How to diagnose and fix it

  1. Verify the code with a scan tool and check for any related codes or freeze-frame data to understand when the fault occurs.
  2. Inspect the wiring harness and connectors for the injector group 'D' for signs of damage, corrosion, or loose pins; repair as needed.
  3. Measure the supply voltage at the injector group 'D' connector with the key on, engine off, and compare to battery voltage; a high reading indicates an open circuit or short.
  4. Check the resistance of each injector in group 'D' using a multimeter and compare to the manufacturer's specification; replace any injector that is out of spec.
  5. Perform a voltage drop test on the supply circuit to identify excessive resistance or a short to voltage.
  6. If the wiring and injectors test good, suspect the PCM; consult the factory service information for specific diagnostic procedures before replacement.
  7. Clear the code and road test the vehicle to confirm the repair, ensuring the code does not return.

What the high voltage reading really means

  • A high voltage on the supply circuit often indicates an open circuit rather than a short to power, because the PCM pulls the circuit high when it detects no current flow.
  • Injector group 'D' is not a standard grouping across all manufacturers; always consult the factory wiring diagram to identify which injectors are included in this group.
  • A faulty ignition coil or spark plug can sometimes cause misfire symptoms that mimic injector group 'D' issues, so misfire codes should be investigated alongside P2157.
  • Corroded grounds or a weak battery can cause erratic voltage readings that set this code, so always check the basics before condemning expensive components.
  • The PCM driver for the injector group may be shared with other circuits, so a failure in one injector can affect the entire group and set multiple codes.

Can I keep driving with P2157?

If the check engine light is on but the engine runs smoothly, you can drive cautiously to a repair shop, but avoid heavy acceleration or towing. If the engine is misfiring, running rough, or stalling, stop driving and have the vehicle towed to prevent damage to the catalytic converter or other components.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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