OBD-II code · Powertrain (generic)
P016B Closed Loop Air/Fuel Ratio Control At Limit - System Too Rich
Closed-loop fuel trim hit its lean correction limit because mixture is structurally too rich. Likely fuel pressure too high, leaking injector, or O2 sensor reporting too lean.
Is it safe to drive with P016B?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyInjector leaking
Symptoms
- Check engine light on
- Increased fuel consumption
- Black smoke from exhaust on acceleration
- Smell of unburned fuel, fouled spark plugs
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Fuel Pressure Regulator, Fuel Injectors, Oxygen Sensor
Related codes
- P0168Fuel Temperature Too High
- P0169Incorrect Fuel Composition
- P016AExcessive Time To Enter Closed Loop Air/Fuel Ratio Control
- P016CClosed Loop Air/Fuel Ratio Control At Limit - System Too Lean
- P016DExcessive Time To Enter Closed Loop Fuel Pressure Control
- P016EClosed Loop Fuel Pressure Control At Limit - Pressure Too High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.