What it means
Bank 2 counterpart to P2253. The Vs negative line on bank 2, sensor 1 reads above the upper threshold.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The upstream oxygen sensor on bank 2 has a negative-current control line that the engine control module monitors as part of interpreting the sensor signal. P2255 sets when that line is detected above the module's upper threshold, despite the code title describing a low circuit condition.
Common causes
Most likely first.
- Vs negative line shorted to positive
- Internal short in sensor
- 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 readings with bank 1 during the same operating conditions to see whether the fault is isolated to bank 2.
- Inspect the bank 2 sensor 1 connector and harness for corrosion, loose pins, heat damage, or contact resistance.
- Check the Vs negative wire for a short to a positive feed, using the vehicle wiring diagram to identify the correct terminals.
- With the sensor disconnected as specified by the service information, check whether the abnormal circuit reading remains on the harness side.
- If wiring and connector checks pass, test the bank 2 sensor 1 negative-current circuit and sensor against the manufacturer's specification.
Common fixes
- Clean or repair corroded bank 2 sensor 1 connector terminals.
- Repair the Vs negative wire if it is shorted to a positive feed.
- Replace the bank 2 sensor 1 oxygen sensor if its internal circuit fails testing.
Can I keep driving?
Usually the vehicle remains drivable, but a faulty bank 2 sensor signal can increase fuel use and emissions. Avoid prolonged driving if it runs roughly, and address it before an emissions test.
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.