P0284 Cylinder 8 Contribution/Balance Fault

P0284 indicates a cylinder 8 contribution or balance fault. Cylinder 8 is contributing less or differently than expected.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Injector
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace injector 8 from a contribution code alone; verify mechanical and fuel delivery causes first.

Useful checks before replacing parts

Compare cylinder 8 contribution, misfire counters, injector balance, compression, fuel pressure, and ignition or glow data if equipped.
Inspect injector flow, injector command, wiring, compression, intake leaks, exhaust leaks, and fuel contamination.
Check whether the imbalance occurs at idle, under load, cold, hot, or with companion injector circuit or misfire codes.

Related OBD-II codes

These nearby injector entries can help compare wording and fault area. They may share the same verification status as the source database.