DTC P0133 O2S Slow Response Sensor 1. Isuzu S/T Isuzu

For 1990-2009 cars only

Makes 🢒 Isuzu 🢒 1999 🢒 S/T Isuzu - 4WD 🢒 DTC 🢒 DTC P0133 O2S Slow Response Sensor 1

Engine Controls Components
Cell 20: EGR Valve, EVAP and IAC Controls
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Circuit Description

The Powertrain Control Module (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 O2S 1 switches from rich to lean and from lean to rich, then adds the amount of time that the O2S 1 took to complete all the switches. With this information, an average time for all switches can be determined. Whenever the average time to switch is too slow, a DTC P0133 will set.

Conditions For Running The DTC

•	DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0200, P0300, P0301, P0302, P0303, P0304, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 are not set.

•	The engine coolant temperature (ECT) is more than 75°C (167°F).

•	The engine speed is between 1800 RPM and 2300 RPM.

•	The engine is operating in closed loop.

•	The throttle position (TP) angle is between 8 percent and 15 percent.

•	The evaporative emissions control system is commanded open for more than 80 percent.

•	The purge learned memory is more than approximately 0.86.

•	The diagnostic completes when 30 seconds of accumulated time has been spent in the above conditions.

Conditions For Setting The DTC

The average O2S 1 response times are more than 249 mS for rich to lean sweeps or 249 mS for lean to rich sweeps.

Ratio of response times is more than 6.0 or less than 0.2.

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 malfunction present.

•	The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.

•	A history DTC stores.

Conditions for Clearing the MIL/DTC

•	The malfunction indicator lamp (MIL) will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault.

•	A history DTC will clear after 40 consecutive warm up cycles without a fault.

•	Use a scan tool to clear the DTCs.

Diagnostic Aids

DTC P0133 or slow response is most likely caused by one of the following:

•	The fuel pressure - The system will go rich if the fuel pressure is to high. The PCM can compensate for some increase, if the fuel pressure gets too high, a DTC P0172 may set. Refer to Fuel System Diagnosis .

•	A leaking fuel injector - A leaking or faulty fuel injector can cause the system to go rich.

•

The 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.

•	The pressure regulator - Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator.

•	The TP sensor - An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating.

•

The O2S 1 contamination - Inspect the O2S 1 for silicone contamination from 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.

Test Description

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

The Powertrain OBD System Check prompts the technician to complete some of the basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information then stores in the scan tool for later reference.

Reprogram the replacement PCMs and perform the crankshaft position system variation procedure. Refer to the latest Isuzu Technical Communications System (ITCS) information for PCM programming and the Crankshaft Position System Variation Learn for the crankshaft position system variation learn procedure.

If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.

DTC P0133-Oxygen Sensor (O2S) Circuit Slow Response (Sensor 1)

Step

Action

Value(s)

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Install a scan tool.
Turn ON the ignition switch leaving the engine OFF.

Were there any component DTCs set?

Go to Component DTC tables

Go to Step 3

Start the engine.
Allow the engine to reach the normal operating temperature.
Operate the vehicle within the parameters specified under Conditions For Setting the DTC.
Monitor the Lean/Rich Avg. (mS), Rich/Lean Avg. (mS), and Rich/Lean to Lean/Rich Ratio on the O2S 1 (greater than, less than).

Do the parameters show averages less than the specified values or ratios less than or greater than the specified values?

249 ms

0.2

6.0

Go to Step 4

Go to Step 17

Turn OFF the ignition switch.

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

Visually/physical inspect the following items:

•	O2S 1 is securely installed.

•	Check for corrosion on the terminals.

•	Check for terminal tension (At O2S 1 and at the PCM).

•	Check the O2S 1 ground circuit for a good connection.

•	Check for damaged wiring.

Was a problem found in any of the above areas?

Go to Step 9

Go to Step 5

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

Check the exhaust manifold for an exhaust leak near the engine.
Repair the leak as necessary.

Was a repair necessary?

Go to Step 3

Go to Step 6

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

Disconnect the O2S 1 electrical connector.
Turn ON the ignition switch leaving the engine OFF.
Monitor the O2S 1 voltage with the scan tool.

Does the scan tool voltage indicate voltage within specified values?

407-509 mV

Go to Step 7

Go to Step 10

Connect a jumper wire to the O2S 1 signal circuit terminal (PCM side) to ground.
Monitor the O2S 1 voltage with the scan tool.

Does the scan tool voltage indicate the voltage below the specified value?

200 mV

Go to Step 8

Go to Step 11

Notice: Determine and correct the cause of the contamination in order to prevent damage to the replacement sensors.

Turn OFF the ignition switch.

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

Replace the Oxygen Sensor (O2S 1). Refer to Oxygen Sensor Replacement .

Is the action complete?

Go to Step 17

Repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

Go to Step 17

Turn OFF the ignition switch.
Repair the short to ground in the O2S 1 sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

Go to Step 17

Remove the jumper wire.
Connect a DMM between the O2S 1 signal circuit and ground.
Measure the voltage between the O2S 1 signal circuit and ground.

Does the O2S 1 voltage measure above the specified value?

407 mV

Go to Step 12

Go to Step 13

Turn OFF the ignition switch.
Disconnect the PCM electrical connectors.
Check the O2S 1 low circuit for continuity.
If the O2S 1 low circuit measures over the stated value, repair the following condition(s) as necessary. Refer to Wiring Repairs in Wiring Systems.

•	Open circuit

•	Poor electrical connection

Was repair necessary?

5ohms

Go to Step 17

Go to Step 14

Turn OFF the ignition switch.
Disconnect the PCM electrical connectors.
Check the O2S 1 sensor signal circuit for continuity.
If the O2S 1 sensor signal circuit measures over the specified value, repair the following condition(s) as necessary. Refer to Wiring Repairs in Wiring Systems.

•	Open circuit

•	Poor electrical connection

Was a repair necessary?

5ohms

Go to Step 17

Go to Step 15

Check the O2S 1 sensor low circuit terminal electrical connection at the PCM.
Replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems.

Did the terminal require replacement?

Go to Step 17

Go to Step 16

Check the O2S 1 sensor signal circuit terminal connection at the PCM.
Replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems.

Did the terminal require replacement?

Go to Step 17

Go to Step 16

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the action complete?

Go to Step 17

Clear the DTCs with the scan tool.
Start the engine.
Allow the engine to idle at the normal operating temperature.
Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?

Go to Step 18

Go to Step 2

Check to see if any additional DTC are set.

Does the scan tool display any DTCs that you have not diagnosed?

Go to applicable DTC table

System OK