HO2S Heater Resistance (Bank 2, Sensor 1)
P0059 indicates the oxygen sensor heater circuit for Bank 2 Sensor 1 is not functioning properly. The heater element in the O2 sensor needs to warm up quickly after engine start to send accurate air-fuel ratio signals to the engine computer.
What You Might Notice
- Diminished fuel efficiency
- Black smoke from exhaust
- Delayed engine startup
- Check Engine Light illuminated
- Possible lean or rich running conditions
Most Common Causes
- 1
Faulty O2 Sensor Heater
The heating element inside the oxygen sensor has failed or burned out, preventing the sensor from reaching operating temperature quickly enough to provide accurate readings.
- 2
Wiring or Connector Issues
The wiring harness to the O2 sensor heater circuit is broken, burnt, or disconnected, interrupting power delivery to the heater element.
- 3
Blown Fuse or Fusible Link
A blown fuse or burnt fusible link in the O2 sensor heater circuit has cut power to the heating element.
- 4
Defective Engine Control Relay
The relay controlling the O2 sensor heater circuit is malfunctioning, preventing proper voltage supply to the heater.
How to Diagnose It
- 1
Check Faulty O2 Sensor Heater — The heating element inside the oxygen sensor has failed or burned out, preventing the sensor from reaching operating temperature quickly enough to provide accurate readings.
- 2
Check Wiring or Connector Issues — The wiring harness to the O2 sensor heater circuit is broken, burnt, or disconnected, interrupting power delivery to the heater element.
- 3
Check Blown Fuse or Fusible Link — A blown fuse or burnt fusible link in the O2 sensor heater circuit has cut power to the heating element.
- 4
Check Defective Engine Control Relay — The relay controlling the O2 sensor heater circuit is malfunctioning, preventing proper voltage supply to the heater.
How to Fix It
- 1
Replace O2 Sensor
Remove the faulty oxygen sensor from Bank 2 Sensor 1 location and install a new OEM or quality replacement sensor with a functioning heater element.
- 2
Repair Heater Circuit Wiring
Inspect the wiring harness and connectors leading to the O2 sensor heater. Replace any burnt, damaged, or disconnected wires and secure connectors properly.
- 3
Replace Blown Fuse
Locate the fuse or fusible link for the O2 sensor heater circuit in the fuse box and replace with the correct amperage rating. Do not exceed the specified amperage.
- 4
Replace Engine Control Relay
If the relay controlling the O2 sensor heater circuit is confirmed faulty, remove and install a replacement relay of the correct specification.
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