P0052 HO2S Heater Control Circuit High (Bank 2 Sensor 1)

The heated oxygen sensor on bank 2 is the upstream sensor (sensor 1, before the catalytic converter), used for mixture control. 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. P0052 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, closed-loop mixture control starts late and cold-start emissions rise. Bank 2 codes occur only on engines with two exhaust banks (V or boxer engines).

Likely causes

Symptoms

• Check engine light on
• Usually no noticeable drivability problem
• Closed-loop control starts late after a cold start
• 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, saabwisonline.com, en.wikipedia.org.