Refer to
Cell 20: Engine Data Sensors-HO2S 1, Ho2S 2
.
Circuit Description
The PCM continuously monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During the monitor period the PCM counts the number of times that the HO2S responds from rich to lean and from lean to rich and adds the amount of time it took to complete all transitions. With this information, an average time for all transitions can be determined. The PCM then divides the rich to lean average by the lean to rich average to obtain a ratio. If the HO2S transition time ratio is not within range, DTC P1134 will be set, indicating that the oxygen sensor is not responding as expected to changes in exhaust oxygen content
Conditions for Running the DTC
| • | No active MAF, TP, IAT, MAP, ECT Sensor, injector circuit, EVAP, fuel trim, or HO2S heater DTCs. |
| • | Mass Air Flow is between 10 and 30 g/s. |
| • | ECT is greater than 50°C (122°F). |
| • | Engine speed is between 1000 and 3000 RPM. |
| • | Above conditions present for a 100 second monitoring period after closed loop. |
Conditions for Setting the DTC
| • | HO2S 1 transition time ratio is less than 0.5 or greater than 5. |
| • | The conditions is present for a 100 second monitoring period. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. |
| • | The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
A malfunction in the HO2S heater ignition feed or ground circuit may cause a DTC P1134 to set. Check HO2S heater circuitry for intermittent faults or poor connections. If connections and wiring are OK and DTC P1134 continues to set, replace the HO2S 1.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Poor terminal connection. |
| Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis , and Connector Repairs Wiring Systems. |
| • | Damaged harness. |
| Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems. |
| • | Inspect the PCM and the engine grounds for clean and secure connections. |
If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.
Test Description
The number below refers to the step number on the Diagnostic Table:
Step | Action | Value(s) | Yes | No | ||||||||
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||||||||||
2 |
Important: : If any DTCs are set (except P0133), refer to those DTCs before proceeding with this diagnostic table.
Note test result does scan tool indicate DTC failed this ignition? | -- | Go to Diagnostic Aids | |||||||||
3 |
Was an exhaust leak isolated? | -- | ||||||||||
Visually/physically inspect the following items:
Was a problem found in any of the above areas? | -- | |||||||||||
5 |
Does the scan tool indicate voltage near the specified value? | 450 mV | ||||||||||
6 |
Does scan tool indicate voltage below specified value? | 300 mV | ||||||||||
7 | Repair condition as necessary. Is the action complete? | -- | -- | |||||||||
8 | Repair open HO2S 1 low signal circuit or grounded HO2S 1 high signal circuit. Refer to Wiring Repairs . Is the action complete? | -- | -- | |||||||||
9 | Repair open HO2S 1 high signal circuit or faulty PCM connections. Refer to Repair in Wiring Repairs . Is the action complete? | -- | -- | |||||||||
10 | Replace HO2S 1 Refer to Heated Oxygen Sensor Replacement . Is the action complete? | -- | -- | |||||||||
11 |
Note test result does scan tool indicate DTC failed this ignition? | -- | System OK |
