Refer to
HO2S Sensors
.
Circuit Description
The PCM continuously monitors the Heated Oxygen Sensor (HO2S) activity. 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 during the 100 second test period. 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 Setting the DTC
- No injector, MAF sensor, TP sensor, EVAP, IAT sensor, MAP sensor, Fuel Trim, EGR, ECT sensor DTCs set
- DTC P0135 (O2 Heater) not set
- The engine has been running at least 2 minutes and is in closed loop.
- Engine speed is between 1000 RPM and 3000 RPM.
- Mass Air Flow is between 15 gm/s and 30 gm/s
- Engine Temperature is greater than 75°C (167°F).
- Above conditions must be present for a 100 second test period.
- Bank 1 HO2S 1 transition time ratio is less than 0.4 or greater than 3.5.
Action Taken When the DTC Sets
| • | The PCM will illuminate the MIL during the second key cycle in which the DTC sets. |
| • | Open Loop fuel control will be in effect. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present. |
| • | A history DTC P1134 will clear after 40 consecutive warm-up cycles have occurred without a fault. |
| • | DTC P1134 can be cleared by using the scan tool Clear Information function or by disconnecting the PCM battery feed. |
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 bank 1 HO2S 1. Review the Fail Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
-
A condition that affects other heated oxygen sensors indicates probable contamination. To avoid damaging replacement sensors, correct the condition which caused the contamination before replacing the affected sensors.
-
This step checks for conditions which may cause the heated oxygen sensor to appear faulty. Correct any of the described conditions if present.
-
To avoid damaging replacement sensors, correct the condition which caused the contamination before replacing the affected sensors.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||
2 |
Important: If any DTCs are set (except P1153, P1154, P1155, and/or P1156), refer to those DTCs before proceeding with this diagnostic chart.
Does scan tool indicate DTC failed this ignition? | -- | Refer to Diagnostic Aids | |||||||||
Did scan tool also indicate P1153, P1154, P1155, and/or P1156 test failed? | -- | |||||||||||
4 |
Was an exhaust leak isolated? | -- | ||||||||||
Visually/physically inspect the following items:
Was a problem found in any of the above areas? | -- | |||||||||||
6 |
Does the scan tool indicate voltage near the specified value? | 450 mV | ||||||||||
7 |
Does scan tool indicate voltage below specified value? | 300 mV | ||||||||||
Replace affected Heated Oxygen Sensors. Refer to Heated Oxygen Sensor Replacement . Important: Before replacing sensors, the cause of the contamination must be determined and corrected.
Is the action complete? | -- | -- | ||||||||||
9 | Repair condition as necessary. Is the action complete? | -- | -- | |||||||||
10 | Repair an open Bank 1 HO2S 1 low signal circuit or a grounded Bank 1 HO2S 1 high signal circuit. Refer to Heated Oxygen Sensor (HO2S) Repair in Electrical Diagnosis. Is the action complete? | -- | -- | |||||||||
11 | Repair open Bank 1 HO2S 1 high signal circuit or faulty PCM connections. Refer to Heated Oxygen Sensor (HO2S) Repair in Electrical Diagnosis. Is the action complete? | -- | -- | |||||||||
12 | Replace Bank 1 HO2S 1. Refer to Heated Oxygen Sensor Replacement . Is the action complete? | -- | -- | |||||||||
13 |
Does scan tool indicate DTC failed this ignition? | -- | System OK |
