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DTC codes / P21xx · Fuel and air metering / P2150

P2150Fuel Injector Group 'B' Supply Voltage Circuit Low

P2150 means the engine computer has detected that the supply voltage feeding the fuel injector group 'B' circuit has dropped below the expected threshold for proper injector operation. The computer monitors this voltage and flags the code when the circuit is low, which can prevent the injectors in that group from firing correctly.

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

Symptoms you may notice

  • Illuminated check engine light, often with no other noticeable symptoms
  • Rough idle or misfire that may be intermittent
  • Engine hesitation or stumble during acceleration
  • Reduced engine power or poor fuel economy
  • Hard starting or stalling, especially when the engine is cold
  • In some cases, the engine may run normally because the fault is intermittent

Common causes, most likely first

  1. Corroded, loose, or damaged electrical connector at the fuel injector group 'B' harness
  2. Chafed or broken wire in the injector supply voltage circuit, often near the engine or a heat source
  3. Blown fuse or faulty relay that supplies power to the injector group 'B' circuit
  4. High resistance in the power feed due to a poor ground connection or corroded splice
  5. Failed fuel injector with an internal short that pulls the supply voltage down
  6. Faulty engine control module (ECM) driver for the injector group 'B' circuit, though this is less common
  7. Voltage drop from a weak battery or charging system that affects the entire injector supply circuit

How to diagnose and fix it

  1. Check for any stored or pending codes and record freeze-frame data to understand when the fault occurs
  2. Inspect the battery and charging system voltage to rule out a general low-voltage condition
  3. Locate and inspect the injector group 'B' harness connectors for corrosion, tightness, and damaged pins
  4. Test the supply voltage at each injector in group 'B' with the key on, engine off, and compare to battery voltage
  5. Perform a voltage drop test on the power feed and ground circuits to find excessive resistance
  6. Check the fuse and relay that feed the injector group 'B' circuit and replace if faulty
  7. If voltage is low at the injectors, trace the circuit back to the ECM and repair any chafed or broken wires

What the voltage test reveals about P2150

  • A common oversight is assuming the injector itself is bad, but a low supply voltage code often points to a wiring or connection issue upstream of the injector.
  • The code can set intermittently due to vibration or heat, so a wiggle test of the harness while monitoring voltage can expose a hidden break.
  • Some vehicles share the injector supply voltage with other components, so a fault in a related circuit can drag down the voltage and set P2150.
  • A weak battery or failing alternator can cause a low voltage condition that mimics a circuit fault, so always verify the charging system first.
  • The ECM may disable the injector group 'B' as a protective measure, leading to a dead cylinder that feels like a failed injector but is actually a voltage supply problem.

Can I keep driving with P2150?

You can drive the vehicle cautiously if the only symptom is the warning light, but avoid heavy acceleration or towing until the fault is repaired. If the engine runs rough or misfires, limit driving to reach a repair shop to prevent damage to the catalytic converter.

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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