Possible Causes
| Possible Causes |
|---|
| EXHAUST LEAK |
| ENGINE MECHANICAL PROBLEM |
| 2/2 O2 SENSOR |
| (K342) O2 SENSOR 2/2 SIGNAL CIRCUIT |
| (K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT |
| (K904) O2 DOWNSTREAM RETURN CIRCUIT |
| FUEL CONTAMINATION |
Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding.