Fuel and air

P02B4 — Cylinder 7 Fuel Injector Restricted Flow

Severity: medium Drive with care, to a shop

What P02B4 means

The engine control unit has detected that the cylinder 7 injector is delivering less fuel than commanded, so that cylinder runs lean. Normally the injector opens for a precisely calculated time and sprays fuel from the pressurized rail. A clogged nozzle or worn injector leaves the cylinder short on fuel.

Symptoms

  • Rough idle or vibration
  • Misfire on cylinder 7
  • Hesitation or loss of power under acceleration
  • Worse fuel economy
  • Check engine light on
  • Stumbling under load

Possible causes

  1. Clogged nozzle on the cylinder 7 injector
  2. Internal injector failure (wear, sticking pintle)
  3. Wiring harness or connector problem: open, short or poor contact
  4. Low fuel pressure from a weak pump, clogged filter or faulty regulator
  5. Contaminated or poor-quality fuel
  6. Intake or vacuum leak skewing the mixture
  7. Rarely, an ECU fault

How to diagnose

  1. Scan all codes and freeze frame data, and look for cylinder 7 misfire codes
  2. Review short and long term fuel trims at idle and under load
  3. Compare cylinder balance or contribution values
  4. Inspect the injector 7 connector and wiring for corrosion, damage and correct circuit resistance
  5. Measure fuel pressure and compare it to the factory spec
  6. Test the injector with a multimeter, scope or by listening for clicks
  7. Check the intake and vacuum hoses for leaks
  8. If needed, remove the injector and test spray pattern and flow on a bench

Common fixes

  • Professional cleaning of the cylinder 7 injector (bench cleaning, not just a fuel additive)
  • Replace the cylinder 7 injector
  • Repair or replace the injector wiring and connector
  • Replace the fuel filter, and the pump or regulator if they test bad
  • Fix any intake air leaks

Questions and answers

Can I drive with code P02B4?

Briefly and without heavy loads, to reach a shop. If the engine shakes badly or the check engine light flashes, stop, since you risk damaging the catalytic converter and engine.

Will a fuel additive fix P02B4?

If the cause is light deposits, an additive may help, but it is not guaranteed. A proper diagnosis and bench cleaning are more reliable, and a worn injector needs replacing.

What does injector restricted mean?

It means less fuel flows through the injector than the ECU expects. A clogged nozzle is the most common cause, but wiring faults or low fuel pressure can also be responsible.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.