P00D4: HO2S Heater Control Circuit Range/Performance Bank 2 Sensor 2

This code concerns the heated oxygen sensor behind the catalytic converter (sensor 2) on bank 2. Unlike the heater circuit codes, which report an open or short circuit, this code means the heater is driven but does not bring the oxygen sensor to the expected temperature. One documented method, used where no current-measuring shunt is fitted, measures the internal impedance of the sensor element: a hot element has a low impedance. If the impedance stays above a limit that depends on the calculated element temperature and the voltage at the sensor connector, the heating is judged insufficient. The test runs once per trip. Typical causes are an aged heating element or added resistance from corrosion in the heater circuit. Bank 2 exists only on V and boxer engines.

Medium severity. Can I keep driving?Yes, you can normally drive in moderation, but get it repaired soon: you will use more fuel and the catalytic converter can be damaged over time.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines. Sensor 2 is the sensor after the catalytic converter.

Symptoms

Check engine light on
Usually no noticeable drivability problem
Oxygen sensor heater readiness stays incomplete

Most likely causes

Heating element aged, resistance increased
Corrosion or contact resistance at connector or harness of the heater circuit
Too low supply voltage at the sensor connector, e.g. poor ground
Diagnostic software (manufacturer updates exist for some vehicles)
Replacement sensor with a different heater

What to check, in order

Start with the simplest. You can tick off each step.

Check the wiring and connector of the sensor indicated
Compare the reading with other engine data while varying the engine speed.
Look for exhaust leaks
Check the signal in live data with the engine warm
Check the fuse and the heater resistance if the code mentions it
Replace the sensor if it has power and does not respond

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P00D4 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
0: Subsystem depends on the code range
D4: Specific fault in that system

Frequently asked questions

Can I keep driving with code P00D4?

Yes, you can normally drive in moderation, but get it repaired soon: you will use more fuel and the catalytic converter can be damaged over time.

What causes code P00D4?

The most common causes are: heating element aged, resistance increased; corrosion or contact resistance at connector or harness of the heater circuit; too low supply voltage at the sensor connector, e.g. poor ground.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.