What it means
The negative current control line (Vs−) of the wide-band lambda sensor on bank 1 sensor 1 is open or out of range. Used as the virtual ground reference for the Nernst cell.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 Sensor 1 is the upstream wide-band oxygen sensor, and its Vs− negative-current control line provides a reference for the sensor’s Nernst cell. The control module sets this code when that line is open or outside its expected range, so the air-fuel reading may be unreliable.
Common causes
Most likely first.
- Vs− line open
- Wide-band sensor failed
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Check freeze-frame data and related oxygen-sensor or fuel-trim codes to see when the Bank 1 Sensor 1 Vs− fault occurred.
- Inspect the upstream Bank 1 Sensor 1 connector and harness for a loose terminal, corrosion, heat damage, or a broken wire.
- Use the wiring diagram to identify the Vs− circuit and check its continuity and connection to the sensor and module as directed by the manufacturer.
- Check for an open or damaged Vs− wire while moving the harness gently to reveal an intermittent connection.
- If the circuit and connectors are intact, test Bank 1 Sensor 1 and its Nernst-cell return using the manufacturer’s procedure.
Common fixes
- Reconnect or clean the Bank 1 Sensor 1 Vs− connector terminals.
- Repair an open or damaged Vs− wire in the sensor harness.
- Replace Bank 1 Sensor 1 if its Vs− circuit or Nernst-cell return has failed internally.
- Repair a confirmed fault in the module-side circuit.
Can I keep driving?
The engine may still run, but incorrect upstream air-fuel readings can increase fuel consumption and emissions or cause roughness. Limit driving if it hesitates or runs poorly, and address 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.