Clogged or restricted fuel injector nozzle due to carbon deposits or debris; Faulty fuel injector solenoid or internal mechanical failure; Wiring harness damage or poor electrical connection at the injector; Low fuel pressure or volume from a weak fuel pump or clogged filter; Contaminated fuel or fuel system corrosion; ECM software issue or faulty injector driver circuit (less common)

DTC codes / P02xx · Fuel and air metering (injector circuits) / P02B4

P02B4Cylinder 7 - Injector Restricted

Q: What does code P02B4 mean?

Cylinder 7 - Injector Restricted. P02B4 indicates that the engine control module (ECM) has detected a restricted fuel injector on cylinder 7, meaning the injector is not delivering the expected amount of fuel for the commanded pulse width. The ECM typically compares crankshaft speed fluctuations or fuel trim corrections across cylinders to identify the imbalance.

P02B4 indicates that the engine control module (ECM) has detected a restricted fuel injector on cylinder 7, meaning the injector is not delivering the expected amount of fuel for the commanded pulse width. The ECM typically compares crankshaft speed fluctuations or fuel trim corrections across cylinders to identify the imbalance.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or misfire sensation, especially when the engine is cold
Reduced engine power or hesitation during acceleration
Poor fuel economy due to the ECM adding fuel to compensate
Shaking or vibration felt through the steering wheel or seat
In some cases, a strong fuel odor from the exhaust or increased emissions

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 poor electrical connection at the injector
Low fuel pressure or volume from a weak fuel pump or clogged filter
Contaminated fuel or fuel system corrosion
ECM software issue or faulty injector driver circuit (less common)

How to diagnose and fix it

Perform a visual inspection of the cylinder 7 injector and its wiring harness for damage or corrosion
Use a scan tool to check fuel trim values and misfire counters to confirm the affected cylinder
Test the injector's electrical resistance and compare it to the manufacturer's specification
Run a fuel pressure and volume test to rule out a supply issue
Perform an injector balance test or cylinder contribution test to verify restriction
Clean the injector with a professional fuel injection cleaning service or replace it if cleaning fails
After repair, clear the codes and verify fuel trims and misfire counters return to normal

Before you replace the injector

A restricted injector often sets no drivability symptoms because the ECM can compensate with fuel trims, so the code may appear during routine scanning.
Fuel pressure problems can mimic a restricted injector; always verify supply pressure and volume before condemning the injector.
Carbon buildup on the injector tip is a common cause that can sometimes be resolved with a targeted cleaning rather than replacement.
Wiring issues at the injector connector are frequently overlooked and can cause intermittent restricted codes.
The ECM may misreport a restricted injector if the crankshaft position sensor signal is erratic, so check for related codes.

Can I keep driving with P02B4?

You can usually continue driving with this code, but avoid heavy acceleration or towing until it is repaired. Prolonged driving with a restricted injector can lead to catalytic converter damage and worsened fuel economy.

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.