EGR CTO

NOTE: Engine coolant temperature should be below 100° F.

1. Check vacuum lines for leaks and correct routing.
2. Disconnect vacuum line at EGR valve and connect a vacuum gauge.
3. Operate engine at approximately 1,500 rpm, no vacuum should be indicated on gauge.

NOTE: If vacuum is indicated, replace EGR CTO switch.

4. Idle engine until coolant temperature exceeds 115° F (black color code), 160° F (yellow color coded) or 100° F on 4-151 engines.
5. Operate engine at 1,500 rpm, ported carburetor vacuum should be indicated on gauge.

NOTE: If vacuum is not indicated, replace EGR CTO switch.