Originally Posted by
Rohan Anwar
My car’s check engine light is on with same code (P0421). Some other codes which I got today are (U0401), (B1062) & (B1042). Any information in this regard would be highly appreciated.
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DTC P0421: Warm Up Catalyst Efficiency Below Threshold
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TECHNICAL DESCRIPTION
The signal from the heated oxygen sensor (rear) differs from the linear air-fuel ratio sensor, because the catalytic converter purifies exhaust gas. When the catalytic converter has deteriorated, the signal from the linear air-fuel ratio sensor becomes similar to the heated oxygen sensor (rear).
The ECM compares the output of the linear air-fuel ratio sensor and heated oxygen sensor (rear) signals.
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DESCRIPTIONS OF MONITOR METHODS
Linear air-fuel ratio sensor and heated oxygen sensor (rear) rich/lean switching frequencies are nearly equal.
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MONITOR EXECUTION
Continuous
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MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
Linear air-fuel ratio sensor monitor
Heated oxygen sensor (rear) monitor
Linear air-fuel ratio sensor heater monitor
Heated oxygen sensor heater (rear) monitor
Heated oxygen sensor offset voltage monitor
Misfire monitor
Fuel system monitor
Heated oxygen sensor (rear) feedback control system monitor
Sensor (The sensor below is determined to be normal)
Mass airflow sensor
Engine coolant temperature sensor
Intake air temperature sensor
Barometric pressure sensor
Throttle position sensor
Accelerator pedal position sensor
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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
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13A-274 MULTIPORT FUEL INJECTION (MFI)
DTC SET CONDITIONS
Logic Flow Chart
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Check Conditions
Engine speed is less than 4,250 r/min <M/T> or 3,500 r/min <CVT>.
Accelerator pedal is depressed.
Mass airflow rate is between 6 and 45 g/sec <M/T> or 10 and 45 g/sec <CVT>.
More than 3 seconds have passed after the above-mentioned three conditions have been met.
Intake air temperature is more than 10C (14F).
Barometric pressure is more than 76 kPa (22.4 in.Hg).
Under the closed loop air/fuel ratio control.
Vehicle speed is more than 1.5 km/h (1.0 mph).
The ECM monitors the maximum 5 times <M/T> or 3 times <CVT> per drive cycle under these conditions.
Short-term fuel trim is between 25 percent and +25 percent.
StartMonitoringconditionsMalfunctionGoodEndNoNoYes YesRf > R0Calculate average frequencyratio (Rf = Fr/Ff) of specified timesR0, R1: Threshold valueACC07077Calculate frequency ofrear oxygen sensor output signal (Fr)Calculate frequency ratio (Rf = Fr/Ff) NoYesRf < R1Specified times monitored?NoYesCalculate frequency offront oxygen sensor output signal (Ff)
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
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MULTIPORT FUEL INJECTION (MFI) 13A-275
The cumulative mass airflow is more than 901 g.
The linear air-fuel ratio sensor rich/lean switching frequency is more than 8 times.
Judgment Criterion
When the monitoring for 10 seconds is carried out 5 times, the frequency ratio of heated oxygen sensor (rear) and linear air-fuel ratio sensor signals is more than the specified value.
NOTE:
The specified value varies depending on the average air flow rate.
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FAIL-SAFE AND BACKUP FUNCTION
None
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OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function OBD-II Drive Cycle Pattern 3 P.13A-10.
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TROUBLESHOOTING HINTS (The most likely causes for this code to be stored are
Catalytic converter deteriorated.
Heated oxygen sensor failed.
Exhaust leak.
ECM 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. Replace the catalytic converter.
(1)Replace the catalytic converter.
(2)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function OBD-II Drive Cycle Pattern 3 P.13A-10.
(3)Check the diagnostic trouble code (DTC).
Q:Is DTC P0421 stored?
YES :
Replace the ECM (Refer to, Removal and Installation P.13A-656).
NO :
The inspection is complete.
Code No. U0401 Engine (CAN message)
CAUTION
If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C CAN Bus Diagnostics Table P.54C-12).
Before replacing the ECU, ensure that the communication circuit is normal.
When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to P.35C-134 and P.35C-135).
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OPERATION
Engine-related signals are sent or received to and from between ASC-ECU and engine control module via CAN bus lines.
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DIAGNOSTIC TROUBLE CODE SET CONDITIONS
This diagnostic trouble code is set when the engine control module malfunction has been detected.
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PROBABLE CAUSES
Malfunction of engine system
Malfunction of engine control module
Malfunction of ASC-ECU
Noise interference
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use the scan tool MB991958 to diagnose the CAN bus lines.
Q:Is the check result normal?
YES :
Go to Step 3.
NO :
Repair the CAN bus line (Refer to GROUP 54C Troubleshooting P.54C-12) On completion, go to Step 2.
STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Q:Is diagnostic trouble code No. U0401 set?
YES :
Go to Step 3.
NO :
This diagnosis is complete.
STEP 3. Check for diagnostic trouble codes of other systems.
Check if diagnostic trouble code(s) other than U0401 is set.
Q:Is the diagnostic trouble code set?
YES :
Follow the relevant diagnostic trouble code procedure, and then go to Step 5.
NO :
Go to Step 4.
DIAGNOSIS
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35C-76 ACTIVE STABILITY CONTROL SYSTEM (ASC)
STEP 4. Use scan tool MB991958 to confirm a diagnostic trouble code of other systems.
Check if the diagnostic trouble code is set in the engine control module (Refer to GROUP 13A Diagnostic Trouble Code Chart P.13A-47).
Q:Is the diagnostic trouble code set?
YES :
Troubleshoot the engine control module diagnostic trouble code. Then go to Step 5.
NO :
Go to Step 5.
STEP 5. Diagnostic trouble code recheck
Check again if the diagnostic trouble code is set.
(1)Erase the set diagnostic trouble code.
(2)Ignition switch: "LOCK" (OFF)
(3)Ignition switch: "ON"
Q:Is diagnostic trouble code No. U0401 set?
YES :
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to P.35C-137).
NO :
The trouble can be an intermittent malfunction (Refer to GROUP 00 How to Cope with Intermittent Malfunction P.00-13).
Code No.B1061: Air outlet damper potentio.high
Code No.B1062: Air outlet damper potentio.low
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DIAGNOSTIC TROUBLE CODE SET CONDITION
This code is stored when the mode selection damper control motor potentiometer does not send any signal to the A/C-ECU due to short or open circuit.
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POSSIBLE CAUSES
Malfunction of the mode selection damper control motor and potentiometer
Damaged the wiring harness or connectors
Malfunction of the auto A/C controller assembly (A/C-ECU).
AUTOMATIC A/C DIAGNOSIS
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55B-12 AUTOMATIC AIR CONDITIONING
DIAGNOSIS
STEP 1. Using scan tool MB991958, check data list.
Check that the following service data display contents are normal.
Item No.55: Air outlet c/o potentiometer
Item No.56: Air outlet c/o potentio.(Target)
Q:Is the check result normal?
YES :
Go to Step 3.
NO :
Go to Step 2.
STEP 2. Check open and short circuit in SENB, MODP and SENG line between mode selection damper control motor and potentiometer connector (potentiometer side) and auto A/C controller assembly (A/C-ECU) connector.
Q:Is the check result normal?
YES :
Go to Step 4.
NO :
Repair the connector(s) or wiring harness.
STEP 3. Check the mode selection damper control motor and potentiometer.
Refer to P.55B-44.
Q:Is the check result normal?
YES :
Go to Step 4.
NO :
Replace the mode selection damper control motor and potentiometer.
STEP 4. Check whether the diagnostic trouble code is stored again.
Q:Is the diagnostic trouble code stored?
YES :
Replace the auto A/C controller assembly (A/C-ECU).
NO :
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction P.00-13).
Code No.B1041: A/M damper potentiometer high
Code No.B1042: A/M damper potentiometer low
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DIAGNOSTIC TROUBLE CODE SET CONDITION
This code is stored when the air mixing damper control motor potentiometer does not send any signal to the A/C-ECU due to short or open circuit.
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POSSIBLE CAUSES
Malfunction of the air mixing damper control motor and potentiometer
Damaged the wiring harness or connectors
Malfunction of the auto A/C controller assembly (A/C-ECU)
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View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)