P0284 code meaning
Cylinder 8 Contribution/Balance
Powertrain system Generic code P02xx codes Check engine light
What P0284 means
P0284 comes from the cylinder balance control of common-rail diesels: the engine module measures the crankshaft acceleration of each cylinder's power stroke, compares it with the average and gives a deviating cylinder more or less fuel. The code sets when the correction for cylinder 8 reaches its limit and the cylinder still does not keep up – GM at 95 % of a limit of about ±12–17 mm³ for 30 s, Ford above 90 % of the allowed 3.5–15 mg per stroke for 7.5 s; GM needs two trips. The code does not say whether there is too much or too little fuel – the correction value for cylinder 8 shows the direction: strongly negative means a leaking injector, strongly positive a weak injector or low compression.
P0284 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0284
- Check engine light on
- Rough idle, shaking or knocking
- Loss of power or smoke
- Higher consumption, poor cold start
Common causes of P0284
- Most likelyInjector of cylinder 8 worn, coked or leaking
- PossibleEngine software outdated or diagnosis too sensitive
- PossibleInjector correction codes not or wrongly programmed after replacement
- PossibleLow compression on cylinder 8 (valve, rings, injector seal)
- Less likelyCrankshaft sensor or tone wheel learning faulty, dual-mass flywheel
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel injector cylinder 8Crankshaft position sensorEngine control module
What each part of P0284 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 2 | Area: fuel and air metering (injector circuit). |
| 84 | The exact fault in that area. |
What to do next
- Note P0284 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0284
What does P0284 mean?
P0284 means "Cylinder 8 Contribution/Balance". P0284 comes from the cylinder balance control of common-rail diesels: the engine module measures the crankshaft acceleration of each cylinder's power stroke, compares it with the average and gives a deviating cylinder more or less fuel. It is a generic code, so it means the same on every make.
Is it safe to drive with P0284?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0284 fail an emissions test?
Yes, it can. P0284 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0284 to fix?
Difficulty: hard. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will P0284 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.