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DTC P1243: Inquiry/Response Error
 
 
 
 
TECHNICAL DESCRIPTION
Monitors the computation function of the ECM.
 
 
DTC SET CONDITIONS
Check Condition
  • Ignition switch is "ON" position.
Judgment Criterion
  • ECM can not calculate input data.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Microcomputer is reset.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • ECM failed.
 
 
 
DIAGNOSIS
Required Special Tool:
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: V.C.I.
    • MB991827: USB Cable
    • MB991910: Main Harness A
STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) After the DTC has been deleted, read the DTC again.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC P1243 set?
Replace the ECM (Refer to, Removal and Installation ).
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 .