OBD-II Code
P0284
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$300–$9,000
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$300 (intake valve walnut blast) to $9,000 (full pump + rail + injector set on a Duramax CP4.2 failure).
P0284 is the cylinder 8 contribution/balance fault — V8 or larger only.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0284 is the cylinder 8 contribution/balance fault — V8 or larger only.
P0284 is the cylinder 8 contribution/balance fault — V8 or larger only. The ECM has determined that cylinder 8 is deviating from the per-cylinder fuel trim average by more than +/- 5 mm3/stroke for a sustained period, meaning either the cylinder is making less torque than commanded (weak compression, restricted injector, valve issue) or more torque than commanded (stuck-open injector, leaking high-pressure fuel seal feeding extra fuel). On Ford modular V8s and Powerstroke V8s, cylinder 8 lives at the rear of the left bank closest to the firewall and transmission bellhousing — physically the hardest cylinder to reach on a 4WD F-Series. On GM LS-series V8s and Duramax V8s, cylinder 8 is also rear left bank.
Cheapest-first ladder
- live cylinder balance trims first (normal 0-3, flagged greater than 5), cutout test second (healthy 80-150 RPM drop, weak less than 50), compression test third (less than 85% of highest cylinder is mechanical), injector electrical and back-leak fourth.
- On diesel V8s also check the glow plug current draw on cyl 8 — a partially shorted glow plug skews combustion temp and creates a contribution fault that mimics injector failure.
- Expensive-misdiagnosis caveat: on Duramax engines specifically, a failing CP4.2 high-pressure pump can shed metal that lands in the rear-most injectors (cyl 7 and cyl 8) first because of fuel rail flow geometry — if you replace cyl 8's injector without inspecting the rail and pump, you'll destroy the new $400-$800 injector within months.
Vehicle-specific patterns2001-2004 GM Duramax LB7 6.6L throws P0284 paired with other balance codes from the well-known LB7 injector failure (cup-style injectors crack and le…
- 2001-2004GM Duramax LB7 6.6L throws P0284 paired with other balance codes from the well-known LB7 injector failure (cup-style injectors crack and leak fuel into the valve cover oil); GM extended warranty to 200k miles on LB7 injectors and the standard fix is replacing all 8.
- 2008-2010Ford 6.4L Powerstroke V8 throws P0284 from piston cracking, oil-cooler restriction, and EGR-cooler contamination — left-bank cylinders fail first because of cooling flow geometry.
- 2011-2016Duramax LML 6.6L throws P0284 from CP4.2 pump failures sending metal contamination through the rail and damaging the rear injectors.
- 2008-2013BMW N63 4.4L V8 (550i, 750i, X5/X6 5.0i) throws P0284 alongside P0281/P0275 in clusters when injectors and coils degrade as a set; BMW's N63 Customer Care Package covers most affected VINs.
- 2010-2017Audi 4.2L V8 FSI throws P0284 from carbon buildup on intake valves of the rear-bank cylinders; walnut-blast service resolves it.
Estimated repair$300 (intake valve walnut blast) to $9,000 (full pump + rail + injector set on a Duramax CP4.2 failure).
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