Powertrain, generic · Fuel and air metering, auxiliary emission controls

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

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

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

Symptoms

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

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–300
Time0.5–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

oxygen sensor downstreamoxygen sensor heateroxygen sensor wiring

Related codes

P0056P0060P0161P00D2

References: law.cornell.edu, newtonnet.co.uk, fordservicecontent.com.