P0044 HO2S Heater Control Circuit High (Bank 1 Sensor 3)

The heated oxygen sensor on bank 1 is the third sensor further downstream, which exists only on systems with two catalyst stages. Its heating element brings it quickly to operating temperature. Typically the heater receives battery voltage via a fuse, and the engine control module switches the ground side with a pulsed signal while checking that the circuit state matches the command. P0044 means the control module sees too high a voltage in the heater control circuit, typically because the switched ground wire is shorted to battery voltage. Which physical fault sets the general, low or high code is defined by each manufacturer. Without heating, the sensor becomes ready late and catalyst monitoring may not complete.

Likely causes

Symptoms

• Check engine light on
• Usually no noticeable drivability problem
• Catalyst monitor does not complete
• Emissions test or readiness check failed

Repair estimate

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

Parts involved

Related codes

References: law.cornell.edu, static.nhtsa.gov, en.wikipedia.org.