Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category |
DTC Descriptors
DTC P2243: O2 Sensor Voltage Signal Circuit Malfunction (Bank 1 Sensor 1)DTC P2247: O2 Sensor Voltage Signal Circuit Malfunction (Bank 2 Sensor 1)
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: Fluctuates above and below 350-500 mV. | |||
Sensor Signal | 0-60 mV | 400-415 mV | 5000 mV |
Low Reference | -- | 400-415 mV | 5000 mV |
Circuit Description
The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started the engine control module (ECM) operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air/fuel ratio. The ECM supplies the HO2S with a reference or bias voltage of about 450 mV. While the engine runs the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the ECM, Closed Loop is entered. The ECM uses the HO2S voltage to determine the air/fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the ECM to calculate the air/fuel ratio sooner.
Conditions for Running the DTCs
DTC P2243 or P2247
| • | The ignition voltage is between 10-16 volts. |
| • | The engine is operating. |
Conditions for Setting the DTCs
DTC P2243 or P2247
The ECM detects that the H02S reference voltage circuit is low.
Action Taken when the DTC Sets
DTCs P2243 and P2247 are type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P2243 and P2247 are type B DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
| • | Allow the engine to reach operating temperature. Engine running, observe the affected HO2S parameter with a scan tool. |
| - | The HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fuelling changes. |
| - | The HO2S 2 value should change more than 200 mV when the throttle is quickly cycled 3 times from Closed to wide open and back to Closed after running the engine at 1,500 RPM for 30 seconds. |
| • | If any HO2S heater DTCs are set, diagnose those DTCs first. |
| • | The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination: |
| ⇒ | Silicon contamination. |
| ⇒ | Engine oil contamination. |
| ⇒ | Engine coolant contamination. |
Circuit/System Testing
- Disconnect the affected HO2S.
- Measure for approximately 450 mV from the affected HO2S reference voltage circuit terminal and a known ground.
- Install a 3-A fusible link wire between the affected HO2S reference voltage circuit terminal and the affected HO2S low signal circuit terminal. The affected HO2S parameter should indicate 0 mV.
- Install a test lamp between the affected HO2S reference voltage circuit terminal and battery voltage. The affected HO2S parameter should indicate approximately 1,095 mV.
- If the ECM and all circuits test normal, replace the affected HO2S.
| ⇒ | If more than approximately 450 mV, test the affected HO2S reference voltage circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If less than approximately 450 mV, test the affected HO2S high signal circuit for high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If not 0 mV and all circuits and connectors test normal, replace the ECM. |
| ⇒ | If not 1,095 mV and all circuits and connectors test normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification.
| • | Engine Control Module Replacement for engine control module replacement, setup and programming. |
