GM Service Manual Online
For 1990-2009 cars only

System Description

The DTC P2433 Secondary Air Injection (AIR) System Pressure Sensor Circuit High Voltage diagnostic detects an out of range sensor signal. The AIR system helps reduce exhaust emissions. The system forces fresh filtered air into the exhaust stream in order to accelerate the catalyst operation. An electric air pump, the AIR pump, provides filtered air on demand to the AIR shut-off valve. The AIR shut-off valve controls the flow of air from the AIR pump to the exhaust manifold. The AIR solenoid valve supplies the manifold vacuum that is used to operate the AIR shut-off valve. A pressure sensor is used to monitor the air flow from the AIR pump. The powertrain control module (PCM) supplies the pressure sensor with a 5-volt reference, an electrical ground, and a signal return circuit that has a 5-volt bias. By comparing the measured pressure against the expected pressure, the pressure sensor can detect faults in the AIR pump, AIR shut-off valve, and the AIR solenoid valve. The pressure sensor can also detect leaks in the AIR system plumbing.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2433 Secondary Air Injection (AIR) System Pressure Sensor Circuit High Voltage

Conditions for Running the DTC

    • The ignition is ON or the engine is running.
    • DTC P2433 runs continuously once the above condition has been met.

Conditions for Setting the DTC

The pressure sensor signal is more than 4.8 volts for at least 0.5 seconds.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL).
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

    • The MIL turns OFF after 3 consecutively passing trips without a fault present.
    • A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
    • A DTC can be cleared by using the scan tool Clear Information function.

Diagnostic Aids

    • An intermittent malfunction may be caused by a fault in an AIR pressure sensor electrical circuits. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .
    • If the DTC 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.
    • Operating the vehicle in Check Mode will increase the ability of the PCM to detect engine control system malfunctions. Refer to Check Mode in Service Bay Test .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The Diagnostic System Check - Vehicle 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. This step determines if DTC P2433 is the result of a hard failure or an intermittent condition. Normal pressure sensor input voltage is approximately 1.6 volts with the ignition ON, AIR pump OFF.

  3. The pressure sensor signal circuit carries a 5-volt bias that can be measured with the DMM. If the measured voltage is near zero there is an open or a faulty PCM.

  4. This step checks for an open in the pressure sensor ground circuit.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn ON the ignition, with the engine OFF.
  2. Backprobe the input circuit of the secondary air injection (AIR) pressure sensor with a DMM to ground.

Is the pressure sensor input circuit voltage within the specified value?

1.5-1.6 V

Go to Step 3

Go to Step 4

3

  1. Use the scan tool in order to clear the DTCs.
  2. Start the engine.
  3. Operate the vehicle within the Freeze Frame conditions as specified or within the Conditions for Running the DTC. Review the supporting text.

Did DTC P2433 set?

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Go to Step 4

Go to Diagnostic Aids

4

Was DTC P0113, DTC P0118, or DTC P0123 also set?

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Go to Step 9

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the pressure sensor electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the pressure sensor input circuit voltage with a DMM.

Is the voltage near the specified value?

4.9 V

Go to Step 7

Go to Step 6

6

  1. Test the pressure sensor input circuit for an open or a short to voltage.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

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Go to Step 12

Go to Step 11

7

Probe the pressure sensor ground circuit on the harness side with a test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 8

8

Repair the open in the sensor ground circuit between the AIR pressure sensor and the splice. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

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Go to Step 12

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9

Repair the open in the sensor ground circuit between the powertrain control module (PCM) and the splice. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

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Go to Step 12

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10

Replace the AIR pressure sensor. Refer to Secondary Air Injection Pressure Sensor Replacement .

Is the action complete?

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Go to Step 12

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11

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Is the action complete?

--

Go to Step 12

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12

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC, as specified by the supporting text.

Does the DTC run and pass?

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Go to Step 13

Go to Step 2

13

With a scan tool, observe the stored information, Capture Info.

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

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Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK