Failed heater element inside the Bank 2 Sensor 1 oxygen sensor; Damaged, chafed or heat-affected wiring to the sensor heater, including open circuit or short to earth or supply; Corroded, loose or contaminated connector at the sensor or in the harness; Blown fuse or faulty relay in the heater supply circuit (depends on model); Exhaust leak or contamination damaging the sensor and its heater; Fault in the ECU heater driver circuit.

P0050

HO2S Heater Control Circuit 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
50: FaultThe specific fault in that area

What it means

P0050 means the engine control unit has detected a fault in the heater control circuit of the upstream oxygen sensor (Sensor 1) on Bank 2, the side of the engine that does not contain cylinder number one. The heater brings the sensor up to working temperature quickly so the ECU can enter closed-loop fuel control. The code sets when the ECU sees a circuit fault such as an open circuit, short or abnormal current on the heater control, and the exact test varies by manufacturer.

Symptoms

Engine warning light on
Slightly higher fuel consumption
Rough or unstable idle, especially from cold
Poor cold-start running or hesitation while the engine warms up
Failed emissions test
Fuel trims running abnormally while the engine is cold

Possible causes

Failed heater element inside the Bank 2 Sensor 1 oxygen sensorlikely
Damaged, chafed or heat-affected wiring to the sensor heater, including open circuit or short to earth or supplylikely
Corroded, loose or contaminated connector at the sensor or in the harnesspossible
Blown fuse or faulty relay in the heater supply circuit (depends on model)possible
Exhaust leak or contamination damaging the sensor and its heaterrare
Fault in the ECU heater driver circuitrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including coolant temperature and engine load, to see the conditions when the fault set.
Confirm that Bank 2 is correctly identified for this engine and which sensor is Sensor 1 (upstream) by checking the workshop data for the specific model.
Visually inspect the sensor wiring and connector for chafing, melting, exhaust heat damage, water ingress and corrosion.
Check the fuse and relay for the heater supply, where fitted, using the vehicle wiring diagram.
Measure the sensor heater element resistance with the connector unplugged and compare it with the manufacturer specification.
With the ignition on, check for correct supply voltage and a proper control signal or earth at the heater circuit, following the wiring diagram.
Check the harness for continuity and for shorts to earth or supply between the sensor connector and the ECU.
Check for exhaust leaks near the sensor and look for signs of contamination, then clear the code and retest to confirm the fix.

How to fix

Replace the Bank 2 Sensor 1 oxygen sensor if the heater resistance is out of specification or the heater is open circuit.
Repair or replace damaged wiring, and secure the harness away from hot exhaust parts.
Clean or replace corroded or damaged connectors and terminals.
Replace a blown fuse only after finding why it failed, and replace a faulty relay.
Repair any exhaust leak and correct the cause of sensor contamination.
If the harness and sensor test good and the fault persists, have the ECU driver circuit checked and repaired as per manufacturer procedure.

Can I keep driving?

Low severity

The car is usually safe to drive in the short term, but book it in soon. A prolonged fault can increase fuel use and emissions and may affect catalyst health if fuel control stays degraded.

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