What it means
The control module detects an open or fault in the reference voltage circuit for the intake air oxygen sensor on bank 1. The sensor reading may be unreliable.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The intake air oxygen sensor on bank 1 provides a signal used to assess oxygen in the intake air, while its reference circuit supplies the voltage needed for reliable readings. P2ABF sets when the control module detects an open or interrupted reference path, so the bank 1 sensor data may be missing or unreliable.
Common causes
Most likely first.
- Open in reference voltage wire
- Intake air O2 sensor failed
- Pin pushed back out of connector body
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Record freeze-frame data and compare bank 1 intake air oxygen sensor and fuel-trim data with bank 2, if fitted, to identify when the fault occurs.
- Locate the bank 1 intake air oxygen sensor using vehicle service information and inspect its connector and harness for damage, corrosion or a backed-out pin.
- Check whether the reference voltage is present at the bank 1 sensor connector using the manufacturer's circuit procedure.
- If the reference is absent, check continuity through the reference wire and inspect its terminals for an open or poor connection.
- If the wiring and connector pass, test the bank 1 sensor and module circuit according to the manufacturer's specification before replacing parts.
Common fixes
- Seat the pushed-back bank 1 connector pin or repair a loose terminal.
- Repair an open or damaged bank 1 reference wire.
- Clean or replace corroded bank 1 sensor connector terminals.
- Replace the bank 1 intake air oxygen sensor if testing confirms its reference circuit has failed.
Can I keep driving?
You can usually drive gently if the engine runs normally, but increased fuel use, hesitation and an emissions failure are possible. Avoid prolonged driving if it runs roughly, since unreliable bank 1 data can affect fueling.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.