P0052

3UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0031,P0032,P0037,P0038,P0051,P0052,P0057,P0058: Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 1)
P0058 - Oxygen Sensor Heater Control Circuit High (Bank 2 Sensor 2)

DESCRIPTION

The heated oxygen sensor is used to monitor oxygen concentration in the exhaust gas. For optimum catalytic converter operation, the air-fuel mixture must be maintained near the ideal stoichiometric air-fuel ratio. The heated oxygen sensor output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. The ECM adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The heated oxygen sensor generates a voltage between 0.1 and 0.9 V in response to oxygen concentration in the exhaust gas.

If the oxygen concentration in the exhaust gas increases, the air-fuel ratio is called lean. The heated oxygen sensor voltage drops below 0.45 V and the heated oxygen sensor informs the ECM of the lean condition.

If oxygen is not in the exhaust gas, the air-fuel ratio is called rich. The heated oxygen sensor voltage increases above 0.45 V and the heated oxygen sensor informs the ECM of the rich condition.

HINT
The ECM has a pulse width modulated control circuit to adjust current through the heater. The heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.

MONITOR DESCRIPTION

The sensing portion of the heated oxygen sensor has a zirconia element which is used to detect the oxygen concentration in the exhaust. If the zirconia element is at the proper temperature and the difference of the oxygen concentration between the inside and outside surface of the sensor is large, the zirconia element will generate voltage signals. In order to increase the oxygen concentration detecting capacity in the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor. When the current in the heated oxygen sensor heater is out of the standard operating range, the ECM interprets this as a fault in the heated oxygen sensor heater. The ECM illuminates the MIL and sets a DTC.

Normally, the heated oxygen sensor heater current is 0.4 to 1.0 A.

Example:

The ECM will set a high current DTC if the current in the sensor is more than 2 A. Similarly, the ECM will set a low current DTC if the current is less than 0.3 A.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

All:

P0031, P0037, P0051, P0057:

P0032, P0038, P0052, P0058 (Case 1):

P0032, P0038, P0052, P0058 (Case 2):

TYPICAL MALFUNCTION THRESHOLDS

P0031, P0037, P0051, P0057:

P0032, P0038, P0052, P0058:

COMPONENT OPERATING RANGE

MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

CONFIRMATION DRIVING PATTERN

- Connect the Techstream to the DLC3.

- Turn the ignition switch to ON and turn the Techstream ON.

- Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).

- Turn the ignition switch off and wait for at least 30 seconds.

- Turn the ignition switch to ON and turn the Techstream on [A].

- Start the engine and idle it for 5 minutes or more [B].

- With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 3000 rpm for 1 minute [C].

- Idle the engine for 5 minutes or more [D].

- Enter the following menus: Powertrain / Engine / Trouble Codes [E].

- Read the DTCs.

HINT
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine / Utility / All Readiness.

- Input the DTC: P0031, P0032, P0037, P0038, P0051, P0052, P0057 or P0058.

- Check the DTC judgment result.

- If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] through [E] again.

- If no DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
WIRING DIAGRAM

INSEPCTION PROCEDURE

HINT
- Read freeze frame data using the Techstream. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
- Bank 1 refers to the bank that includes No. 1 cylinder.
- Bank 2 refers to the bank that does not include No. 1 cylinder.
- No. 1 cylinder is located in the front part of the engine, opposite the transmission.
- Sensor 1 refers to the sensor closest to the engine body.
- Sensor 2 refers to the sensor farthest away from the engine body.
PROCEDURE

1. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

(a) Disconnect the H9, H10, H15 and H16 sensor connectors.

(b) Measure the resistance of the sensor.

Standard Resistance (Bank 1 Sensor 1):

Standard Resistance (Bank 2 Sensor 1):

Standard Resistance (Bank 1 Sensor 2):

Standard Resistance (Bank 2 Sensor 2):

NG -- REPLACE HEATED OXYGEN SENSOR
OK -- Continue to next step.

2. INSPECT EFI RELAY

(a) Remove the EFI relay from the engine room No. 2 relay block.

(b) Measure the resistance of the EFI relay.

Standard Resistance:

NG -- REPLACE EFI RELAY
OK -- Continue to next step.

3. CHECK ECM (HT1A, HT2A, HT1B, HT2B VOLTAGE)

(a) Turn the ignition switch to ON.

(b) Measure the voltage of the ECM.

Standard Voltage:

NG -- CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)

OK -- REPLACE ECM Service and Repair

4. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)

(a) Disconnect the H9, H10, H15 and H16 sensor connectors.

(b) Disconnect the E2, E4 and E5 ECM connectors.

(c) Measure the resistance of the wire harness side connectors.

Standard Resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - EFI RELAY)

(a) Disconnect the H9, H10, H15 and H16 sensor connectors.

(b) Remove the EFI relay from the engine room No. 1 relay block.

(c) Measure the resistance of the wire harness side connectors.

Standard Resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- CHECK ECM POWER SOURCE CIRCUIT ECM Power Source Circuit