Code 32 - EGR System Failure

EGR vacuum is regulated by an ECM-controlled solenoid. The solenoid is normally closed. The vacuum source is a ported signal. The ECM turns the EGR on and off (duty cycle) by grounding and ungrounding circuit No. 435. The duty cycle is calculated by the ECM based on coolant temperature, airflow and engine RPM. The duty cycle should be zero percent (no EGR) when vehicle is in Park or Neutral, TPS input below a specified value, or TPS indicating Wide Open Throttle (WOT).

With the ignition on and engine stopped, the EGR solenoid is de-energized unless the diagnostic terminal is grounded. Code 32 means the EGR vacuum diagnostic switch was closed during start-up, or that the switch was not detected closed under the following conditions:

• Coolant temperature greater than a specified amount.
• EGR duty cycle command is greater than 50-55 percent.
• TPS less than half throttle, but not at idle.
• Manifold vacuum greater than 7 in. Hg.
• All conditions above must be met for 5 seconds.

If the switch is detected closed during start-up, or if switch is detected open when above conditions are met, the "SERVICE ENGINE SOON" light will remain on unless the switch changes state.

1. If the first test caused Code 32 to set, then the ECM has recognized a closed vacuum switch on start-up. This test will determine whether the EGR vacuum diagnostic switch is the cause or if the wiring or the ECM is the cause.
2. With the ignition on, the solenoid should not be energized and vacuum should not pass to the EGR valve.
3. At this point the EGR solenoid and valve are okay and the next test will check the diagnostic vacuum switch portion of the system.
4. The diagnostic switch should close at about 2 in. Hg of vacuum. With vacuum applied, the switch should close and resistance go to near zero ohms. Vacuum should hold.

Fig 1: Code 32, EGR System Failure, Schematic

Fig 2: Code 32, EGR System Failure (1 Of 2)

Fig 3: Code 32, EGR System Failure (2 Of 2)