Kia Ceed
A UK/EU Ceed diagnostic approach: split trims (idle vs load), use misfire evidence, and prove EVAP/air leaks before parts-darting.
Quick triage
Capture
- Codes + freeze-frame
- STFT/LTFT at idle + 2,000 rpm
- Misfire counters per cylinder (if available)
- EVAP purge (if after-refuel symptoms)
Interpretation
- Lean idle-only → intake leak/PCV path.
- Lean under load → fuel delivery/MAF/MAP bias/boost leak.
- Repeating cylinder misfire → ignition/injector/mechanical evidence path.
- After-refuel rough idle → purge valve behaviour.
Common complaints
- Intermittent idle shake: verify trims; a small leak can mimic coil problems.
- Hesitation on acceleration: check trims + plausibility before condemning turbo/DPF/cat.
- P0420: confirm stable upstream control and no misfires.
Typical OBD2 codes
P0300
Random misfire: evidence-first.
P0171
Lean: idle vs load split is everything.
P0420
Cat efficiency: don’t skip upstream checks.
P0442
EVAP small leak: cap vs purge/vent logic.
What makes owners come back: don’t guess. Use trims + evidence to choose the correct branch. It’s faster, cheaper, and repeatable.
Trust note: These profiles are designed to narrow possibilities. Confirm with test data (trims, misfire counters, pressure/smoke tests, voltage checks) before buying parts.