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Inspection procedure 3: The malfunction indicator lamp (SERVICE ENGINE SOON or check engine lamp) remains illuminated and never goes out
 
 
 
 
COMMENT
  • In cases such as the above, the cause is probably that the ECM is detecting a problem in a sensor or actuator, or that one of the malfunctions listed below has probably occurred.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this case: )
  • Combination meter failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is any DTC stored?
Refer to, Diagnostic Trouble Code Chart .
Go to Step 2.
 
STEP 2. Check the trouble symptoms.
(1) Turn the ignition switch to the "ON" position.
  • The malfunction indicator lamp (SERVICE ENGINE SOON or Check Engine Lamp) should go out after the engine was started.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
Does the malfunction indicator lamp (SERVICE ENGINE SOON or Check Engine Lamp) go out?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Check the combination meter system. Refer to GROUP 54A, Combination Meter - Trouble Symptom Chart .