P02BB

What it means

P02BB means the engine control unit has found that the individual fuel correction for cylinder 9 has reached its minimum limit. It is taking away as much fuel as it can from that cylinder and still sees a rich condition, or believes it does. Which cylinder is number 9 and how the cylinder-specific trim is calculated depend on the engine, so check the manufacturer data for the model.

Symptoms

• Engine management light on
• Rough idle or uneven running
• Smell of fuel or black smoke from the exhaust
• Higher than normal fuel consumption
• Possible misfire codes alongside
• Hesitation or reduced power under load

Possible causes

• Leaking or sticking injector on cylinder 9 delivering too much fuellikely
• Injector wiring, connector or driver fault on cylinder 9 causing incorrect injector operationpossible
• Restricted airflow to cylinder 9, such as carbon build-up on the inlet valve or port, or a faulty intake valve or actuatorpossible
• Faulty or contaminated exhaust oxygen or air-fuel ratio sensor on the bank serving cylinder 9, giving a false rich readingpossible
• Ignition fault or poor combustion in cylinder 9 that upsets the mixture readingpossible
• Excessive fuel pressure or contaminated fuel, usually affecting more than one cylinderrare
• Outdated or faulty control unit software, where the manufacturer has identified it as a causerare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting engine load, temperature and fuel trim values when the code set.
2. Check for other fuel trim, misfire, injector or sensor codes, as these narrow down the cause and show whether other cylinders are affected.
3. Look at live data for individual cylinder fuel trim and overall bank trims, and see whether cylinder 9 is the only one at its limit.
4. Inspect the cylinder 9 injector connector, wiring and earth for damage, corrosion, fuel or oil contamination and poor pin tension.
5. Check the injector electrical resistance and signal pattern against the manufacturer specification, and carry out an injector balance or leak-down test if the model allows.
6. Check the ignition components on cylinder 9 and look at the spark plug condition for signs of running rich, such as black sooty deposits.
7. Measure fuel pressure against specification and check the operation of the oxygen or air-fuel ratio sensor on the relevant bank.
8. Inspect the inlet port and valves for deposits or restrictions, and check the intake valve control system if the engine has one.

How to fix

• Replace the leaking or faulty injector on cylinder 9 and clear the code once the repair is verified.
• Repair or replace damaged injector wiring, connectors or terminals.
• Clean or repair the inlet port and valves, or fix the intake valve control fault, to restore normal airflow.
• Replace a faulty oxygen or air-fuel ratio sensor once testing has confirmed it is giving false readings.
• Replace worn spark plugs or faulty ignition components on cylinder 9.
• Correct fuel pressure faults or drain and replace contaminated fuel, and update the control unit software only if the manufacturer lists it as a fix.

Can I keep driving?

Nearby codes

• P02BAGenericCylinder 9 - Fuel Trim at Max Limit
• P02BCGenericCylinder 9 - Injector Restricted