What it means
The positive-current control circuit for the oxygen sensor at Bank 2 Sensor 1 is below its expected range. The code identifies a circuit condition, not a confirmed failed sensor.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
A wide-band oxygen sensor uses a pump cell to help measure exhaust oxygen, and the engine control module monitors the positive-current control circuit for Bank 2 Sensor 1, the upstream sensor on bank 2. This code sets when that circuit reads below its expected range, which can result from a sensor fault or a problem in the circuit.
Common causes
Most likely first.
- Pump cell open or sensor failed
- Pumping current line shorted to ground
- Connector pins corroded - high contact resistance
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 2 Sensor 1 live readings with the corresponding upstream sensor on bank 1 to see when the low-circuit fault appears.
- With the exhaust cool, inspect the Bank 2 Sensor 1 connector and harness for corrosion, loose pins, heat damage, or contact with the exhaust.
- Check the positive-current control wire for a short to ground or an open, following the vehicle wiring diagram and the manufacturer's test procedure.
- Measure circuit continuity and connector contact condition against the manufacturer's specification, including while gently moving the harness to reveal an intermittent connection.
- If the wiring and terminals pass, test the sensor pump cell and control circuit as specified before replacing the sensor.
Common fixes
- Clean or repair corroded or loose Bank 2 Sensor 1 connector terminals.
- Repair a damaged positive-current control wire or short to ground.
- Replace the Bank 2 Sensor 1 oxygen sensor if its pump cell fails the specified test.
- Repair the control module circuit only if testing confirms its output is faulty.
Can I keep driving?
The vehicle may remain drivable, but fuel economy and running quality can worsen and emissions testing may fail. Avoid prolonged driving if it runs roughly or hesitates, since incorrect oxygen feedback 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.