Failed heater element inside the Bank 2 Sensor 1 oxygen sensor (resistance out of range); Damaged, chafed or heat-affected wiring to the sensor heater circuit; Corroded, loose or contaminated connector terminals at the sensor plug; Blown fuse or faulty relay supplying the heater circuit (depends on the vehicle's wiring layout); Low or unstable supply voltage due to a poor earth or battery and charging problems; Faulty heater driver in the engine control unit.

P0059

HO2S Heater Resistance Bank 2 Sensor 1.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
0: AreaFuel and air metering, auxiliary emission controls
59: FaultThe specific fault in that area

What it means

P0059 is the generic code for a heater resistance fault in the heated oxygen sensor on Bank 2, Sensor 1, which is upstream of the catalytic converter on the side of the engine without cylinder number one. The control unit measures the heater circuit's current or resistance and sets the code when the reading is outside the expected range compared with a healthy sensor. Without a working heater the sensor takes too long to reach operating temperature, so closed-loop fuel control is delayed.

Symptoms

Engine warning light on
Slightly higher fuel consumption
Rough or unstable idle after a cold start
Delayed entry into closed-loop fuel control, giving a rich mixture when cold
Failed emissions test or readiness monitors not completing

Possible causes

Failed heater element inside the Bank 2 Sensor 1 oxygen sensor (resistance out of range)likely
Damaged, chafed or heat-affected wiring to the sensor heater circuitlikely
Corroded, loose or contaminated connector terminals at the sensor plugpossible
Blown fuse or faulty relay supplying the heater circuit (depends on the vehicle's wiring layout)possible
Low or unstable supply voltage due to a poor earth or battery and charging problemspossible
Faulty heater driver in the engine control unitrare

How to diagnose

Read the stored codes and freeze frame data, noting engine temperature and whether other oxygen sensor or heater codes are present.
Confirm Bank 2 location from the engine layout, as the bank numbering depends on the model and engine.
Visually inspect the sensor wiring along its whole length for chafing, melting near the exhaust, or damage, and check the connector for corrosion, bent pins or water ingress.
Check the heater circuit fuse and relay if fitted, using the wiring diagram for the specific vehicle.
With the sensor unplugged, measure the heater element resistance across the heater terminals and compare it with the manufacturer's specification.
Check for battery voltage and a good earth/switched control at the sensor connector with the ignition on, following the vehicle's wiring diagram.
Check battery condition and charging voltage, since low voltage can upset heater readings.
Clear the code and road test, then recheck live data to see whether the code returns and the sensor reaches operating behaviour.

How to fix

Replace the Bank 2 Sensor 1 oxygen sensor if the heater resistance is out of specification.
Repair or replace damaged wiring, and secure it away from hot exhaust parts.
Clean or replace corroded connector terminals and ensure the plug is fully seated and sealed.
Replace a blown fuse or faulty relay after finding out why it failed.
Repair poor earths or correct battery and charging faults.
If all wiring and the sensor test fine, have the control unit driver circuit diagnosed and repaired or replaced as per the manufacturer's procedure.

Can I keep driving?

Low severity

The car can normally be driven while you arrange a repair, but expect slightly higher fuel use and keep an eye on any change in running. Fix it reasonably soon to avoid extra fuel use and a possible emissions test failure.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.