Clogged or restricted fuel injector nozzle due to carbon deposits or debris; Faulty fuel injector solenoid or internal mechanical failure; Wiring harness damage or corroded connector at the cylinder 3 injector; Low fuel pressure from a weak pump or restricted filter, though this usually affects multiple cylinders; Contaminated fuel or fuel system deposits that partially block the injector; Engine control module software issue or faulty driver circuit for the injector

DTC codes / P02xx · Fuel and air metering (injector circuits) / P02A4

P02A4Cylinder 3 - Injector Restricted

Q: What does code P02A4 mean?

Cylinder 3 - Injector Restricted. P02A4 indicates that the powertrain control module has detected a restricted fuel injector on cylinder 3, meaning the injector is not delivering the expected amount of fuel for the commanded pulse width. The computer typically compares crankshaft speed fluctuations or fuel trim corrections and flags this code when cylinder 3 consistently underperforms.

P02A4 indicates that the powertrain control module has detected a restricted fuel injector on cylinder 3, meaning the injector is not delivering the expected amount of fuel for the commanded pulse width. The computer typically compares crankshaft speed fluctuations or fuel trim corrections and flags this code when cylinder 3 consistently underperforms.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or engine misfire that may be more pronounced when cold
Noticeable loss of power or hesitation during acceleration
Shaking or vibration felt through the steering wheel or seat
Decreased fuel economy due to the engine compensating for the lean condition
In some cases, a strong fuel odor from the exhaust if the injector is stuck partially open

Common causes, most likely first

Clogged or restricted fuel injector nozzle due to carbon deposits or debris
Faulty fuel injector solenoid or internal mechanical failure
Wiring harness damage or corroded connector at the cylinder 3 injector
Low fuel pressure from a weak pump or restricted filter, though this usually affects multiple cylinders
Contaminated fuel or fuel system deposits that partially block the injector
Engine control module software issue or faulty driver circuit for the injector

How to diagnose and fix it

Perform a visual inspection of the cylinder 3 injector connector and wiring for damage or corrosion
Check fuel pressure and volume to rule out a system-wide supply issue
Use a scan tool to monitor fuel trims and misfire counters on cylinder 3 while running
Run a fuel injector balance test or cylinder contribution test to confirm the restriction
Add a quality fuel injector cleaner to the tank and drive the vehicle to see if the restriction clears
Remove and professionally clean or replace the cylinder 3 fuel injector if cleaning does not resolve the issue
Clear the code and verify the repair with a test drive and live data review

Before you replace the injector

A restricted injector can sometimes be caused by a failing fuel pressure regulator that sends debris downstream, so check system pressure first.
The code may set intermittently if the restriction is minor, and a simple fuel additive can sometimes restore flow without injector removal.
Do not overlook a faulty ignition coil or spark plug on cylinder 3, as a misfire from ignition can mimic an injector restriction and set similar codes.
On direct-injection engines, carbon buildup on the injector tip is a common cause that may require specialized cleaning equipment.
Always verify the injector part number and flow rate match the engine's requirements if replacement is necessary, as mismatched injectors can cause new drivability issues.

Can I keep driving with P02A4?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration or towing loads because the lean condition on cylinder 3 can lead to elevated exhaust temperatures and potential catalytic converter damage. If the check engine light begins flashing, stop driving immediately and have the vehicle towed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.