Faulty oxygen sensor heater element or internal short in the sensor; Damaged, chafed or melted wiring in the heater control circuit shorted to voltage; Corroded, loose or contaminated connector at the sensor or control unit; Wiring harness near the exhaust damaged by heat or rubbing; Fault in the heater driver inside the engine control unit; Incorrect or low quality replacement sensor with the wrong heater specification.

P0064

HO2S Heater Control Circuit High Bank 2 Sensor 3.

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
64: FaultThe specific fault in that area

What it means

P0064 means the control unit has detected a high voltage or short to voltage fault in the heater control circuit of the heated oxygen sensor on Bank 2, Sensor 3. Sensor 3 is the third sensor on that bank, usually fitted downstream of the catalytic converter further along the exhaust. The control unit switches the heater on and off and monitors the circuit, and it set the code because the signal did not match what it expected for the commanded state.

Symptoms

Engine warning light on
No noticeable change in driving in many cases
Slightly longer time to enter closed loop fuel control after a cold start
Possible failed emissions test
Other oxygen sensor or catalyst monitor codes stored alongside it

Possible causes

Faulty oxygen sensor heater element or internal short in the sensorlikely
Damaged, chafed or melted wiring in the heater control circuit shorted to voltagelikely
Corroded, loose or contaminated connector at the sensor or control unitpossible
Wiring harness near the exhaust damaged by heat or rubbingpossible
Fault in the heater driver inside the engine control unitrare
Incorrect or low quality replacement sensor with the wrong heater specificationrare

How to diagnose

Read all stored codes and freeze frame data to see engine temperature and conditions when the fault set, and note any related sensor or heater codes
Confirm which physical sensor is Bank 2 Sensor 3 for this model and engine, as the layout varies
Visually inspect the sensor wiring and connectors for heat damage, chafing, corrosion and water ingress
Check the heater supply and control wiring at the sensor connector against the manufacturer wiring diagram, looking for voltage where there should be none on the control wire
Measure the heater element resistance at the sensor and compare it with the specification for that vehicle
Check the wiring for shorts to voltage between the sensor connector and the control unit with the ignition off and the connectors disconnected
Check for fuse and relay faults supplying the heater circuit where the model uses them, and for any applicable control unit software updates
Clear the code and road test, then recheck that it has not returned and that the sensor heater operates

How to fix

Replace the oxygen sensor if the heater element or internal circuit is faulty, using the correct specification part
Repair or replace damaged wiring and secure it away from hot or moving parts
Clean or replace corroded or damaged connectors and terminals
Repair the short to voltage in the harness between the sensor and control unit
Replace or repair the control unit only after the wiring and sensor have been proven good
Apply a manufacturer control unit software update only if one is known to address this fault on that model

Can I keep driving?

Low severity

The car can normally be driven while you arrange a repair, as this fault rarely affects safety or causes engine damage. Get it fixed soon to avoid emissions test failure and in case the wiring fault worsens.

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