Air/Fuel Mixture: Testing and Inspection

10. INSPECT CO/HC
a. Start the engine.
b. Rev the engine at 2,500 rpm for approximately 180 seconds.
c. Insert CO/HC meter testing probe at least 40 cm (1.3 ft) into the tailpipe during idling.
d. Check CO/HC concentration at idle and/or 2,500 rpm.

HINT:
^ Complete the measuring within 3 minutes.
^ Check regulations and restrictions in your area when performing 2 mode CO/HC concentration testing (engine check at both idle speed and at 2,500 rpm).

e. If the CO/HC concentration does not comply with regulations, troubleshoot in the order given.
1. Check heated oxygen sensor operation.





2. See the table on the next page for possible causes, and then inspect and repair.