P016B
Closed Loop Air/Fuel Ratio Control At Limit System Too Rich
Generic OBD-II
Common symptoms
What you'll notice
- Check and clean the mass airflow sensor (MAF)
- Inspect and replace faulty oxygen sensor(s)
- Check and repair any vacuum leaks in the intake system
- Ensure proper fuel pressure and delivery from the fuel pump and injectors
- Inspect and replace a clogged or malfunctioning catalytic converter
Common causes
Most likely first
- Faulty oxygen sensor
- Clogged or dirty fuel injectors
- Malfunctioning mass air flow sensor
- Vacuum leak in the intake manifold
- Faulty fuel pressure regulator
How to diagnose & fix
Work through it in order
- Decreased fuel efficiency
- Rough idle or stalling
- Check engine light illuminated
- Strong smell of fuel from exhaust
- Lack of power or hesitation during acceleration
Read & clear P016B yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.