What it means
Bank 2 counterpart to P2252. The Vs negative line on the wide-band oxygen sensor at bank 2, sensor 1 is below the lower threshold.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 2 Sensor 1 is the upstream wide-band oxygen sensor on the engine’s second cylinder bank, and its Vs− negative-current line provides a reference for the Nernst cell. The control module sets this code when that circuit’s signal falls below its expected range, which can result from a short to ground, an internal sensor return fault, or a poor connection.
Common causes
Most likely first.
- Vs negative line shorted to ground
- Nernst cell return open inside 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
- Review freeze-frame data and related oxygen-sensor or fuel-trim codes to see when Bank 2 Sensor 1’s Vs− signal went low.
- Inspect the Bank 2 Sensor 1 connector and harness for corrosion, loose terminals, or wiring chafed through to ground.
- Use the wiring diagram to identify the Bank 2 Sensor 1 Vs− circuit and check for a short to ground as directed by the manufacturer.
- Check the circuit and connector for an open or high-resistance connection using the manufacturer’s procedure.
- If the wiring passes inspection and circuit tests, test Bank 2 Sensor 1’s internal Nernst-cell return and the module-side circuit.
Common fixes
- Clean and secure corroded or loose Bank 2 Sensor 1 connector terminals.
- Repair a Vs− wire shorted to ground or replace the damaged harness section.
- Replace Bank 2 Sensor 1 if its internal Nernst-cell return is faulty.
- Repair a confirmed module-side circuit fault.
Can I keep driving?
The engine may still run, but an unreliable Bank 2 upstream mixture reading can increase fuel consumption and emissions or cause roughness. Limit driving if it hesitates or runs poorly, and repair the fault 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.