Code No. P0121: Trustful Check Throttle Position Sensor (main)
FUNCTION
- Compare the actual measurement of volumetric efficiency
by an air flow sensor signal with volumetric efficiency estimated from a throttle position sensor
(main) signal.
TROUBLE JUDGMENT
Check Conditions
- Difference between the actual volumetric efficiency and the volumetric efficiency
estimated by the throttle position sensor (main) is more than 0 %. Or, the volumetric
efficiency is less than 60 %.
- Engine speed is more than 750 r/min.
- Difference between the actual volumetric efficiency and the volumetric efficiency
estimated by the throttle position sensor (main) is more than 33 %.
FAIL-SAFE AND BACKUP FUNCTION
- Throttle opening degree is restricted.
- Throttle opening degree position is in default position if throttle position sensor
(sub) fails.
PROBABLE CAUSES
- Failed throttle position sensor (main)
- Harness damage in throttle position sensor (main) circuit or loose connector contact
- Failed intake air system
- There is some foreign matter around air flow sensor
- Failed engine-ECU
DIAGNOSIS PROCEDURE |
STEP 1. M.U.T.-III diagnosis code |
Q.
Is any other diagnosis code than P0121 set?
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Inspection chart for diagnosis code (Refer to ). |
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Go to Step 2. |
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STEP 2. M.U.T.-III data list |
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Q.
Is the check result normal?
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Go to Step 3. |
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Check throttle position sensor (main) system (Refer to Code No. P0122: Throttle
Position Sensor (main) Circuit Low Input , P0123: Throttle Position Sensor
(main) Circuit High Input ). |
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STEP 3. Check air intake from intake hose and inlet manifold. |
Q.
Is the check result normal?
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Go to Step 4. |
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Repair. |
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STEP 4. Check air flow sensor. |
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Q.
Is the check result normal?
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Go to Step 5. |
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Repair. |
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STEP 5. M.U.T.-III diagnosis code |
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Q.
Is diagnosis code set?
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Replace the engine-ECU. |
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunctions ). |
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