Partially blocked or clogged cylinder 8 injector (deposits or debris); Injector internal fault, such as a sticking pintle or weak coil, giving reduced flow; Low fuel pressure or restricted fuel supply (weak pump, blocked filter, faulty regulator), though this usually affects other cylinders too; Wiring, connector or driver circuit fault at the cylinder 8 injector causing weak or intermittent operation; Contaminated or poor-quality fuel causing deposits; Air leak near cylinder 8 (intake gasket or vacuum leak) mimicking a lean condition; Outdated or faulty control unit calibration where the manufacturer has issued a known update for injector monitoring.

P02B8

Cylinder 8 - Injector Restricted.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
B8: FaultThe specific fault in that area

What it means

P02B8 is the generic code for a restricted fuel injector on cylinder 8. The engine control unit has judged that cylinder 8 is receiving less fuel than it has commanded, or that the cylinder is running leaner or weaker than the others. It usually reaches this conclusion from fuel trim, misfire or crankshaft speed data. The exact detection method varies by manufacturer and engine.

Symptoms

Rough idle or a noticeable misfire on one cylinder
Hesitation or loss of power under acceleration
Poor fuel economy
Hard starting or extended cranking
Engine warning light on, possibly flashing if misfires are severe
Fuel trim readings running lean on the affected bank

Possible causes

Partially blocked or clogged cylinder 8 injector (deposits or debris)likely
Injector internal fault, such as a sticking pintle or weak coil, giving reduced flowlikely
Low fuel pressure or restricted fuel supply (weak pump, blocked filter, faulty regulator), though this usually affects other cylinders toopossible
Wiring, connector or driver circuit fault at the cylinder 8 injector causing weak or intermittent operationpossible
Contaminated or poor-quality fuel causing depositspossible
Air leak near cylinder 8 (intake gasket or vacuum leak) mimicking a lean conditionrare
Outdated or faulty control unit calibration where the manufacturer has issued a known update for injector monitoringrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting load, engine speed, temperature and fuel trims when the code set
Check for other fuel, misfire or lean codes, which help separate a single-injector fault from a general fuel supply problem
Inspect the cylinder 8 injector connector and wiring for damage, corrosion, loose pins or heat damage
Compare live fuel trims and misfire counters for cylinder 8 against the other cylinders at idle and under load
Check fuel pressure against the manufacturer's specification, including pressure holding after shutdown, using the correct procedure for the engine
Test the injector's coil resistance and driving signal, and compare with the specification or the other injectors
Swap the cylinder 8 injector with another cylinder where the layout allows and see whether the fault follows the injector
Check for intake air leaks and inspect the spark plug on cylinder 8 for signs of a lean mixture

How to fix

Clean or replace the restricted cylinder 8 injector, following the manufacturer's guidance for the engine
Repair or replace damaged wiring or connectors to the injector
Replace the fuel filter, fuel pump or pressure regulator if fuel supply faults are confirmed
Drain and replace contaminated fuel and refill with good quality fuel
Repair any intake air leaks found
Apply a manufacturer calibration update only if a relevant bulletin confirms it addresses this fault

Can I keep driving?

Medium severity

Short, gentle journeys are usually possible, but a lean or misfiring cylinder can overheat the catalytic converter and damage the engine over time. Get it checked soon, and stop driving if the warning light flashes or the engine runs very roughly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.