P0137moderate severityPowertrain
O2 Sensor Circuit Low Voltage Bank 1 Sensor 2
on 2003 Mini Cooper 1.6L I4 · FWD
What this code means
The downstream O2 sensor on Bank 1 is reading low voltage consistently.
Symptoms
- Check Engine Light
- Failed emissions
Common causes
- Faulty sensor
- Exhaust leak after cat
- Wiring short to ground
Diagnostic steps
- Test sensor voltage
- Check for exhaust leaks
- Inspect wiring
Repair notes
Replace sensor or repair leak.
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Bluetooth code reader (~$25)
Veepeak OBDCheck BLE →
Pairs with your phone — reads and clears codes, live data.
Serious DIY (~$100)
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
Shop-grade tablet (~$300+)
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
As an Amazon Associate, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Other Powertrain codes on this vehicle
29CC
Misfire Cylinder 1
29CD
Misfire Cylinder 2
29CE
Misfire Cylinder 3
29CF
Misfire Cylinder 4
29D0
Misfire Cylinder 5
29D1
Misfire Cylinder 6
29D2
Misfire Cylinder 7
29E0
Lambda Additive/Idle Adaptation Limit, Bank 1
29E1
Lambda Additive/Idle Adaptation Limit, Bank 2
29E2
Lambda Multiplicative Part-Load Adaptation Limit, Bank 1