Check Engine Indicator Light Concerns
- Perform KOEO On-Demand Self-Test
If CHECK ENGINE light is always on, check for Diagnostic Trouble Codes (DTC). Perform KOEO ON-DEMAND SELF-TEST
under QUICK TEST in SELF-DIAGNOSTICS - 7.3L DIESEL article. If no DTCs are present, go to next step. If any DTCs are present, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS
in SELF-DIAGNOSTICS - 7.3L DIESEL article and perform appropriate SYSTEM TESTS.
- Run Bulb Check
Cycle ignition switch. If CHECK ENGINE light illuminates then goes out (bulb check), no problem is indicated. If CHECK ENGINE light is always off or always illuminated, go to TEST NB: CHECK ENGINE LIGHT
, step 3)
(Econoline), or step 1)
(Excursion and F250-550) under SYSTEM TESTS in SELF-DIAGNOSTICS - 7.3L DIESEL article.