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DTC codes / P2Bxx · Hybrid propulsion / P2B03

P2B03Cylinder 4 Injection Pulse Performance

P2B03 indicates that the powertrain control module (PCM) has detected an abnormal condition in the electrical circuit that controls the fuel injector for cylinder 4, meaning the pulse width or current flow is outside the expected range. The PCM monitors injector performance and sets this code when the commanded injection pulse does not match the feedback signal, often due to a wiring fault, a failing injector, or a driver circuit issue inside the PCM.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Rough idle or misfire sensation, especially when the engine is cold
  • Reduced engine power or hesitation during acceleration
  • Poor fuel economy due to improper fuel delivery
  • Possible engine vibration or shaking at idle
  • In some cases, the engine may enter limp mode to protect the catalytic converter

Common causes, most likely first

  1. Faulty fuel injector on cylinder 4 (coil winding open or shorted, or mechanically clogged)
  2. Damaged or corroded wiring harness or connector at the cylinder 4 injector
  3. Open or short circuit in the injector control wire between the PCM and the injector
  4. Failed injector driver inside the PCM (less common but possible)
  5. Poor electrical ground connection for the injector circuit
  6. Aftermarket or incorrect injector installed previously

How to diagnose and fix it

  1. Perform a visual inspection of the cylinder 4 injector connector and wiring for damage, corrosion, or loose pins
  2. Use a noid light or injector pulse tester to verify that the PCM is sending a command signal to the injector
  3. Measure the resistance of the cylinder 4 injector with a multimeter and compare it to the manufacturer's specification
  4. Check for continuity and short-to-ground on the injector control circuit between the PCM and the injector
  5. Swap the cylinder 4 injector with a known-good injector from another cylinder (if accessible) to see if the code moves
  6. If the circuit and injector test good, diagnose the PCM driver circuit or replace the PCM as a last resort
  7. Clear the code and perform a road test to verify the repair and ensure the code does not return

Don't overlook the injector driver circuit

  • A common mistake is replacing the injector without checking the wiring harness, which often suffers from heat damage or chafing near the cylinder head.
  • The PCM may set this code even when the injector itself is functioning, if the feedback signal is corrupted by a poor ground or electrical interference.
  • A clogged or dirty injector can cause a performance code without completely failing, so flow testing and ultrasonic cleaning are worthwhile before replacement.
  • This code is specific to the injection pulse performance, not a generic misfire code, so focus on the electrical control of the injector rather than ignition components.
  • On some vehicles, a weak battery or charging system issue can cause voltage spikes that disrupt injector control and set this code intermittently.

Can I keep driving with P2B03?

You can drive the vehicle short distances to a repair shop, but avoid heavy acceleration or towing, as a faulty injector can cause misfires that may damage the catalytic converter over time. If the engine is running very rough or lacks power, it is safer to have the vehicle towed.

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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