All Other Models
- With engine at normal operating temperature, connect a CO meter to exhaust gas back-pressure line. Read and record exhaust gas CO value.
- Next, disconnect and plug vacuum line from straight connection of thermo valve. Again check CO value of exhaust gas. System is functioning properly if exhaust gas CO value increases when vacuum line is disconnected. If not, check condition of all system vacuum lines and connections. Repair as necessary.
- If all vacuum lines and connections are okay, and thermo valve is functioning correctly, replace diverter valve.