P0147

DTC P0147 HO2S Heater Circuit Bank 1 Sensor 3 (1 OF 2):

DTC P0147 HO2S Heater Circuit Bank 1 Sensor 3 (2 OF 2):

HO2S Circuit:

Circuit Description
The Vehicle Control Module (VCM) supplies a voltage of approximately 0.45 volts (45 mV) between the HO2S High and HO2S Low circuits.

If this voltage is measured using a 10 megohm digital voltmeter, the voltage may read as low as 0.32 volt. The Heated Oxygen Sensor (HO2S) varies the voltage within a range of about 1.0 volt (1000 mV) if the exhaust is rich to as low as 0.10 volt (10 mV) if the exhaust is lean.

When HO2S temperature is below 360°C (600°F), the sensor will not produce any voltage and will behave like an open circuit. This will result in an Open Loop operation.

The HO2S heater provides for faster sensor warm-up which allows the sensor to become active in a shorter period of time. The sensor will remain active during a long extended idle. The DTC P0147 determines if the HO2S heater is functioning properly by monitoring the amount of time necessary for the HO2S to become active after start-up. This DTC is a type B DTC.

Conditions For Setting The DTC

^ The system voltage is greater than 9 volts but less than 17 volts.
^ The Mass Air Flow (MAF) is less than 27 grams per second.
^ The engine run time is greater than 2 seconds.
^ The Engine Coolant Temperature (ECT) sensor is less than 32°C.
^ The Intake Air Temperature (IAT) sensor is less than 32°C.
^ The difference between the ECT and IAT is no more than 5°C.
^ The elapsed time in order to obtain ±0.150 volts from the HO2S bias voltage (0.300-0.600 volts) is greater than the calculated value.

Action Taken When The DTC Sets
With a current DTC set, the VCM turns on the Malfunction Indicator Lamp (MIL) after 2 consecutive test failures.

Conditions For Clearing The MIL/DTC
The VCM turns the MIL off after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 40°F from the start-up coolant temperature and the engine coolant temperature exceeds 160°F during that same ignition cycle) or the scan tool clearing feature has been used.

Diagnostic Aids
Perform the following checks:

^ Poor connection.
^ Damaged harness-Inspect the harness connectors for the following items:

- Backed out terminals.
- Improper mating.
- Broken locks.
- Improperly formed or damaged terminals.
- Poor terminal to wire connection.
- Damaged harness.

NOTE: Never solder the HO2S wires. For proper wire and connector repairs, refer to Diagrams.

Test Description
The numbers below refer to the step numbers in the diagnostic table.

2. This step determines if the DTC P0147 is the result of a hard failure or an intermittent condition. With the ignition ON and the engine off, the HO2S (Bank 1, Sensor 3) voltage displayed on the scan tool should gradually change 0.150 volt, indicating that the heater is working properly. The HO2S voltage can rise as high as 975 mV before it toggles back down. The main thing to look for is a change.
3. Probing the terminal D of the HO2S (Bank 1, Sensor 3) connector verifies if the voltage is available to the HO2S (Bank 1, Sensor 3) heater.