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DTC P050B: Ignition Timing Retard Insufficient
 
 
 
 
TECHNICAL DESCRIPTION
  • After starting the engine in the cold state, the ECM retards the ignition timing to early activate the catalyst by letting out the high temperature exhaust gases.
  • The ECM monitors whether the retard ignition timing control is normal or not.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • After starting the engine in the cold state, the retard ignition timing control is abnormal, which is caused by a decrease in idle speed and so on.
 
 
MONITOR EXECUTION
  • Once per driving cycle
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
Check Conditions
  • Under the ignition timing retard control.
  • Engine coolant temperature is between 7°C (45°F) and 41°C (106°F).
Judgment Criterion
  • For 10 seconds, the target/specified ignition timing subtracted from the basic ignition timing is less than 3 degrees on average during the retard control.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Throttle valve area is dirty.
  • 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. Check the throttle body. (throttle valve area)
Is the throttle valve area dirty?
Perform cleaning. Refer to, Throttle Body (throttle valve area) Cleaning . Then go to Step 3.
Go to Step 2.
 
STEP 2. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P050B set?
Replace the ECM (Refer to, Removal and Installation ). Then go to Step 3.
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 .
 
STEP 3. Test the OBD-II drive cycle.
(1) Carry out test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P050B set?
Retry the troubleshooting.
The inspection is complete.