P0059Powertrain
Powertrain · SAE
O2 Sensor Heater Resistance — Bank 2, Sensor 1
Meaning
The ECU measured the heater element resistance of the upstream O2 sensor on bank 2 outside the specified range. The abnormal value indicates a degraded heater element or a circuit anomaly altering the current measured by the ECU.
Common causes
- Partially deteriorated internal heater element (out-of-tolerance resistance)
- Partial short circuit in the heater circuit
- High contact resistance in bank 2 connector or wiring (corrosion)
- O2 sensor B2S1 aged or thermally damaged
- Rare: ECU internal measurement issue
Symptoms
- Check engine light (MIL) on
- Possible lambda signal inaccuracy on bank 2 due to incorrect sensor temperature
- Slightly increased fuel consumption
- Generally no obvious drivability symptoms
Severity
Low to moderate: bank 2 sensor performance is compromised but serious drivability issues are uncommon.
What to do
- Measure heater resistance at B2S1 connector pins and compare with OEM values
- Inspect bank 2 connector and wiring for corrosion or loose contacts
- Check voltage drop across wiring during operation
- Replace O2 sensor B2S1 if resistance is out of specification