P050B

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 stored 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 36°C (97°F).
Judgement 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 Monitors, Trips, Drive Cycles and Readiness Codes.

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)

Q. Is the throttle valve area dirty?

YES Perform cleaning. Refer to, Throttle Body (throttle valve area) Cleaning Throttle Body Cleaning.
Then go to Step 3.
NO 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 Monitors, Trips, Drive Cycles and Readiness Codes.

(2)Check the diagnostic trouble code (DTC).

Q. Is DTC P050B set?

YES Replace the ECM (Refer to, Removal and Installation Removal and Replacement).
Then go to Step 3.
NO It can be assumed that this malfunction is intermittent. 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 Monitors, Trips, Drive Cycles and Readiness Codes.

(2)Check the diagnostic trouble code (DTC).

Q. Is DTC P050B set?

YES Retry the troubleshooting.
NO The inspection is complete.