Circuit Description
The PCM continuously monitors the oxygen sensor 1 (O2S 1) activity for 100 seconds. During the monitor period, the PCM counts the number of times that the OS2 1 switches from rich to lean and from lean to rich. With this information, a total for all switches can be determined. If the number of switches is too low, a DTC P1133 will be set.
Conditions for Setting the DTC
| • | When one or more of the following DTC's P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0441, P0562, P0563, P1171, P1441 are not present. |
| • | The number of lean to rich counts is less than 10 or the rich to lean counts is less than 15. |
| • | Engine speed is between 1825 RPM and 2275 RPM. |
| • | TP angle is between 8.2% and 14%. |
| • | Evaporate Emissions Control system is commanded open greater than 50% PWM. |
| • | Purge the learned memory is greater than approximately 192. |
Action Taken When the DTC Sets
| • | Malfunction Indicator Light (MIL) illuminates after two consecutive driving cycles with the fault active. |
| • | Vehicle will operate in open loop. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after passing three consecutive diagnostic tests. |
| • | A history DTC will clear after 40 consecutive ignition cycles have occurred without a fault. |
| • | History and current DTCs can be cleared by using a scan tool. |
Diagnostic Aids
DTC P1133 is most likely caused by one of the following:
| • | Fuel pressure - The system will go rich it fuel pressure is too high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0132 will be set. Refer to Fuel System Diagnosis, Chart A-7. |
| • | Leaking injector - A leaking or faulty injector can cause the system to go rich. |
| • | MAP sensor - An output that causes the PCM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the PCM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the sensor is disconnected. |
| • | Pressure regulator - Check or a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator. |
| • | TP sensor - An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating. |
| • | O2S contamination - Inspect the O2S for silicone contamination from the fuel or use of improper RTV sealant. The sensor may have a white powdery coating and result in a high but false voltage signal (rich exhaust indication). The PCM will then reduce the amount of fuel delivered to the engine causing a severe surge or driveability problem. |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||
1 | Was the On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to OBD System Check | ||||||||
2 | Are any component DTC's set? | -- | Go to component DTC charts | Go to Step 3 | ||||||||
3 |
Do the parameters show fewer transitions than the specified values? | 10 15 | Go to Step 4 | Go to Diagnostic Aids | ||||||||
4 | Visually/physically inspect the following items:
Was a problem found in any of the above areas? | -- | Go to Step 9 | Go to Step 5 | ||||||||
5 | Check the exhaust manifold for an exhaust leak near the engine. Repair as necessary. Was an exhaust leak found? | -- | Go to Step 3 | Go to Step 6 | ||||||||
6 |
Does scan tool voltage indicate voltage below specified value? | 407-509 mV | Go to Step 7 | Go to Step 10 | ||||||||
7 |
Does scan tool voltage indicate voltage below specified value? | 200 mV | Go to Step 8 | Go to Step 11 | ||||||||
8 | NOTICE: Before replacing the sensors, the cause of the contamination must be determined and corrected. Replace the oxygen sensor 1.
Is the action complete? | -- | Go to OBD System Check | -- | ||||||||
9 | Repair condition as necessary. Is the action complete? | -- | Go to OBD System Check | -- | ||||||||
10 | Repair the O2S 1 signal circuit for a short to ground. Is the action complete? | -- | Go to OBD System Check | -- | ||||||||
11 |
Does O2S 1 voltage measure above the specified value? | 407 mV | Go to Step 12 | Go to Step 13 | ||||||||
12 |
Was the O2S 1 low circuit problem found and corrected? | 5 ohms | Go to OBD System Check | Go to Step 14 | ||||||||
13 |
Was the O2S signal circuit problem found and corrected? | 5 ohms | Go to OBD System Check | Go to Step 15 | ||||||||
14 | Check the O2S 1 low circuit terminal connection at the PCM and replace the terminal if necessary. Did the terminal require replacement? | -- | Go to OBD System Check | Go to Step 16 | ||||||||
15 | Check the O2S 1 signal circuit terminal connection at the PCM and replace the terminal if necessary. Did the terminal require replacement? | -- | Go to OBD System Check | Go to Step 16 | ||||||||
16 | Replace the PCM. Is the action complete? | -- | Go to OBD System Check | -- | ||||||||
