P016CClosed Loop Air/Fuel Ratio Control At Limit - System Too Lean
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- With closed-loop control the engine module corrects the injected fuel using the oxygen sensor: short-term fuel trim reacts within fractions of a second, long-term trim stores a learned base correction per load and speed range. Positive values mean fuel is being added because the mixture was lean, negative values mean fuel is being removed; around ±10 % is normal. P016C means the mixture control as a whole has reached its upper limit: it already adds as much fuel as allowed and still cannot reach lambda 1. In substance it matches P0171, without a bank reference. Hyundai documents it on the 2021 Elantra 2.0: if the fuel adaptation was learned wrongly after starts below −10 °C, the engine could stall when stopping or at idle and set P016C; new engine software changed the learning logic. Otherwise the usual lean causes apply: air leaks, low fuel delivery or an air flow sensor reading low.
- What you may notice
- Check engine light on (after two drive cycles)
- Stalling when stopping or at idle
- Rough idle, hesitation
- Often together with P0171
- Likely causes
- LikelyAir leak (intake, crankcase ventilation)
- PossibleFuel pressure or delivery too low
- PossibleWrongly learned adaptation / control module software
- RareAir flow or pressure sensor reading low, injectors clogged
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.