Powertrain, generic (extended)

P230F Cylinder 6 Air-Fuel Ratio Imbalance - Adjustment At Limit During Balance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P230F is the balance-limit code for cylinder 6 and can only appear on engines with six or more cylinders, inline sixes, V6 units and larger. On a V6, cylinder 6 shares its bank and front oxygen sensor with two others, so its individual trim has to be estimated from that bank signal or from crankshaft speed. No maker documents P230F publicly, and no NHTSA bulletin mentions it. The series jumps from here to P231A for cylinder 7, because P2310 to P2319 are taken by ignition coil codes. Mercedes, which uses the series on its AMG M177 V8, shows that such a code can also be a software matter. Checks for cylinder 6 follow the usual order: injector delivery, intake sealing at that port, compression and valve tightness. P21A1 and P0306 belong to the same cylinder.

Likely causes

Injector of cylinder 6 delivering too much or too little (deposits, wear)

Air leak at the intake port or injector seal of cylinder 6

Valve of cylinder 6 not sealing (worn seat or guide), low compression

Poor contact at the connector of injector 6

Symptoms

Check engine light on
Rough idle, possibly misfire on cylinder 6
Higher fuel consumption or exhaust smell

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€0–1,500

Time0.5–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injector cyl 6intake manifoldcylinder compression

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.