Fuel and air

P02B8 — Cylinder 8 Fuel Injector Restricted

Severity: medium Drive with care, to a shop

What P02B8 means

P02B8 means the engine control module has determined that the cylinder 8 injector is delivering less fuel than it should. Normally the ECM opens each injector for a calculated time to deliver an exact amount of fuel. A clogged or worn injector leans out that cylinder, which leads to misfires and poor performance.

Symptoms

  • Rough or uneven idle
  • Misfires, especially under load
  • Loss of power or hesitation
  • Reduced fuel economy
  • Check engine light on
  • Vibration or stumbling while driving

Possible causes

  1. Clogged or carbon-fouled injector on cylinder 8
  2. Mechanical failure or wear inside the injector
  3. Wiring or connector fault in the injector circuit
  4. Low fuel pressure (pump, regulator, filter)
  5. Contaminated or poor-quality fuel
  6. Air leak upsetting the air-fuel mixture

How to diagnose

  1. Scan all codes and freeze frame data, and check for misfires on other cylinders
  2. Review short-term and long-term fuel trims on the bank with cylinder 8
  3. Run a cylinder balance or injector cutout test with a scan tool and compare cylinder 8 to the others
  4. Inspect the injector connector and harness, then check coil resistance, power and the control signal
  5. Measure fuel pressure and compare it to spec
  6. Check for intake vacuum leaks and exhaust leaks
  7. Swap the cylinder 8 injector with a neighbor and see if the fault follows it

Common fixes

  • Clean and flow-test the injector professionally
  • Replace the cylinder 8 injector
  • Repair or replace damaged wiring or connectors
  • Fix fuel pressure problems: filter, pump or regulator
  • Replace the fuel if contamination is confirmed

Questions and answers

What does P02B8 mean?

The ECM sees too little fuel flowing through the cylinder 8 injector. Most often the injector is clogged, but wiring or low fuel pressure can also be to blame.

Can I drive with code P02B8?

A short drive to a shop is usually OK, but extended driving risks overheating and damaging the catalytic converter from misfires. If the check engine light flashes, stop the engine.

Will a fuel injector cleaner fix P02B8?

It can help with light deposits, but it isn't guaranteed. Confirm first that the injector is the cause and not wiring or fuel pressure.

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.