What it means
The bank 1 sensor 2 oxygen sensor negative current control circuit is above the expected range. The code does not by itself establish a short to voltage or predict mixture effects.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 Sensor 2 is the downstream oxygen sensor on the bank containing cylinder 1. The control module monitors the negative, or sinking, side of its pumping-current control circuit and sets this code when the circuit reads above its expected range; that does not by itself prove a short to battery voltage.
Common causes
Most likely first.
- Short to B+
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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 check live Bank 1 Sensor 2 readings to confirm when the negative current-control circuit goes high.
- Inspect the negative current-control wire and connector for pinching against a power source, heat damage, corrosion, or loose terminals.
- Use the wiring diagram to trace the negative current path and check for an unintended connection to battery voltage.
- Check terminal contact and circuit continuity with the manufacturer's procedure.
- If the harness is intact, test the downstream sensor and control-module circuit to the manufacturer's specification.
Common fixes
- Repair wiring pinched against a power source or damaged by heat.
- Clean or repair corroded or loose connector terminals.
- Correct a confirmed short to battery voltage in the negative current-control circuit.
- Replace the sensor or repair the module only if testing confirms an internal fault.
Can I keep driving?
If the engine runs normally and the warning light is steady, keep driving to necessary trips and avoid hard acceleration until the circuit is checked. Incorrect control of Bank 1 Sensor 2 can affect emissions monitoring and fuel economy.
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.