Visual Check
- IG "OFF" & Disconnect HO2S (S1) connector.
- Check that HO2S (S1) is contaminated or damaged by foreign materials.
- Has a problem been found?
YES
- Go to "CHECK HO2S (S1) PERFORMANCE " procedure.
NO
- Substitute with a known - good HO2S (S1) and check for proper operation. If the problem is corrected, replace HO2S (S1) and go to "VERIFICATION OF VEHICLE REPAIR " procedure.