C-1F ~ Oxygen Sensor Heater (HO2S) Heater

Code 13 Circuit Diagram:

Chart C-1F O2 Sensor Heater Circuit Diagnostic Chart:

CIRCUIT DESCRIPTION:

The alternator charging circuit supplies battery voltage to the heater element of the O2 sensor. The heater element warms the sensor to allow varying voltage to be produced by the sensor faster than if it had to rely on exhaust gas only.

TEST DESCRIPTION: Numbers below refer to the circled numbers on the diagnostic chart.

1. This will verify that battery voltage is present at the sensor.

2. Checks ground circuit to the heater.

3. Checks heater element resistance.