Infiniti QX60
A diagnostic baseline for QX60 complaints. Start with data (voltage, trims, freeze-frame), then prove basics before parts.
Quick triage (5 minutes)
What to capture
- All codes + freeze-frame (RPM, load, coolant temp)
- Battery/charging voltage (engine off / running, lights+fan on)
- STFT/LTFT at idle and steady cruise (~2,000 rpm)
- Misfire counters (if available) and O2 status once warm
- If EVAP codes: note if symptoms follow refuelling
What it usually means
- Lean trims at idle only → unmetered air / purge influence; smoke-test before ignition parts.
- Random misfire + stable trims → ignition or mechanical; use counters + swap tests.
- EVAP small leak codes → cap/vent/hoses; confirm with a smoke test of the EVAP system, not guesses.
- P0420 → only evaluate after misfire and mixture control are stable.
Common complaints (and the honest starting point)
- Rough idle / intermittent misfire: separate trims (air/fuel control) from cylinder-specific misfire. Don’t shotgun coils without data.
- Long crank after refuel: classic EVAP purge influence pattern — confirm via trims on restart and purge command.
- “Many warnings” after battery issues: voltage stability is a first step; low system voltage can create misleading codes.
What NOT to do (high-confidence traps)
- Don’t chase catalyst codes before you stabilise misfire/mixture control.
- Don’t assume “fuel pump” without proving trims and pressure behaviour.
- Don’t ignore EVAP codes if you have refuel-related symptoms.
Typical OBD2 codes you’ll see
P0171
Lean condition: trim logic and smoke-testing.
P0300
Random misfire: counters + mixture separation.
P0456
EVAP small leak: test before replacing parts.
P0420
Catalyst efficiency: upstream issues that mimic a bad cat.
Data that settles the argument
Log trims at idle and steady cruise, then watch misfire counters during the symptom. If trims swing lean at idle but settle at cruise, you’re usually chasing unmetered air or purge influence — not a pump.
Trust note: These profiles narrow possibilities. Confirm with test data (trims, misfire counters, smoke testing, voltage checks) before buying parts.