Chevrolet Cobalt Service & Repair Manual: EGR Functional Tests

Fuel Injected Gasoline Engine

The EGR systems used on fuel injected engines are controlled by the ECM. The ECM will store a code in memory when the EGR system malfunctions. Refer to appropriate "Diagnostic Code Identification Chart" for code number.

Linear EGR Valve

1. Connect Tech 1 Scan Tool, or equivalent, to DLC following tool manufacturer's instructions.
2. Correct any DTCs that may be present, particularly those pertaining to MAP sensor fault conditions.
3. Start engine and operate at approximately 1500 RPM, then select MISCELLANEOUS TEST, EGR CONTROL with scan tool.
4. EGR valve should cycle through 25% through 100% positions.
5. Engine RPM should drop and idle should roughen as EGR valve is cycled.

PCM & ECM Controlled EGR Valve

This EGR system is controlled by ECM or PCM, which will store a code in memory when EGR system is faulty.
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    See also:

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    Chevrolet Cobalt Owners Manual

    Chevrolet Cobalt Service Manual


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