What it means
The ECM detects that the injection pulse on cylinder 5 does not produce the expected combustion result. Pulse width, timing, or quantity drift compared to the bank average.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The ECM estimates how cylinder 5 responds to its injector command by comparing combustion behavior and injection data with the other cylinders on the same bank. This code sets when cylinder 5's injection pulse performance falls outside the expected pattern, which can happen as its injector's flow changes or fuel quality affects combustion.
Common causes
Most likely first.
- Injector aged - flow characteristic drifted
- Fuel quality affecting injection result
Symptoms
- Check-engine light may be on
- Rough idle or engine vibration
- Hesitation or reduced power
How to diagnose it
- Record freeze-frame data and compare cylinder-specific misfire or fuel-balance data at the conditions that set P2B04 to see whether the issue is confined to cylinder 5.
- Check fuel level and recent refuelling history, and note whether the roughness began after a change in fuel.
- Inspect cylinder 5's injector connector and wiring for looseness, corrosion, chafing, or heat damage.
- Compare cylinder 5 injector command and contribution data with the other cylinders using a scan tool, including when the engine is warm.
- If the data continues to point to cylinder 5, have its injector flow and spray performance assessed against the manufacturer's specification.
Common fixes
- Correct a poor-fuel issue by using the appropriate fuel and monitoring whether the symptom returns.
- Repair a loose, corroded, or damaged cylinder 5 injector connector or wiring.
- Clean or service the cylinder 5 injector if testing identifies deposits and the injector is serviceable.
- Replace the cylinder 5 injector if its flow performance is outside the manufacturer's specification.
Can I keep driving?
If the engine runs smoothly and the warning light is steady, limit driving and arrange diagnosis soon because poor combustion can increase emissions and may damage the catalytic converter. Stop driving if the light flashes, vibration becomes severe, or power loss makes the vehicle unsafe.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.