P0135

DTC P0135 Heated Oxygen Sensor (HO2S) Heater Circuit - Sensor 1 (1 Of 2):

DTC P0135 Heated Oxygen Sensor (HO2S) Heater Circuit - Sensor 1 (2 Of 2):

Heated Oxygen Sensor (HO2S) Circuit:

CIRCUIT DESCRIPTION


The Heated Oxygen Sensor (HO2S) are used to minimize the amount of time required for closed loop fuel control operation and allow accurate catalyst monitoring. The oxygen sensor heater greatly decreases the amount of time required for fuel control (HO2S) sensor 1) to become active. The oxygen sensor heater is required by catalyst monitor (HO2S sensor 2) to maintain a sufficiently high temperature. This allows accurate exhaust oxygen content readings from the engine.

CONDITIONS FOR SETTING THE DTC

- Current of the HO2S heater is 4 amps or more, or less than 0.22 amps, with heater ON.

- Voltage of the HO2S heater is 13.75V or higher, or lower than 10V, with heater ON.

- Voltage of the HO2S heater is 6V, with heater OFF.

- One of the above conditions present for 3 seconds.


ACTION TAKEN WHEN THE DTC SETS

- The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.

- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.


CONDITIONS FOR CLEARING THE MIL/DTC

- The MIL will turn "OFF" after three consecutively passing cycles without a fault present.

- A History DTC will clear after 40 consecutive warm-up cycles without a fault.

- DTC(s) can be cleared by using a scan tool or by disconnecting the ECM battery feed.


DIAGNOSTIC AIDS


Check the following conditions:

- Poor connection at ECM. Inspect harness connectors for backed out terminal, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

- Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the HO2S 1 display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the HO2S 1 display will indicate the location of the fault.

If DTC P0135 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.


If any wiring repairs need to be made, Refer to Repair Procedures in Diagrams.


TEST DESCRIPTION

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Engine OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. Determines if fault is present.

3. The HO2S 1 is powered by the IG Coil Meter fuse located in Fuse Block 1.

5. Measure the resistance of the heater portion of the HO2S1.