- DTC judgment completed
- System normal
Lexus NX: Cold Start Idle Air Control System Performance (P050A)
Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (engine Control) / Sfi System / Cold Start Idle Air Control System Performance (P050A)
MONITOR DESCRIPTION
This monitor will run when the engine is started at an engine coolant temperature of -10 to 50°C (14 to 122°F). The DTC will be stored after the engine idles for 13 seconds (2 trip detection logic).
The DTC is designed to monitor the idle air control at cold start. When the engine is started at an engine coolant temperature of less than 50°C (122°F), the ECM measures the accumulated mass air flow during engine idling. If the accumulated mass air flow does not reach the specified level within 10 seconds, the ECM interprets this as a malfunction. The MIL is illuminated and a DTC is stored when the malfunction is detected in consecutive driving cycles (2 trip detection logic).
The electronic throttle control system controls the idle speed. The electronic throttle control system operates the throttle actuator to open and close the throttle valve, and adjusts the intake air amount to achieve the target idle speed.
NOTICE:
The idle speed control learned values are cleared by performing a learned value reset. Idle speed control learning needs to be performed before this DTC can be stored.
HINT:
Idle speed control learning* is performed when the engine is warmed up and has been idling for 5 minutes.
*: Refer to Initialization.
Click here .gif)
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory |
|---|---|---|---|---|---|
| P050A | Cold Start Idle Air Control System Performance | Insufficient mass air flow after a cold start (2 trip detection logic). |
| Comes on | DTC stored |
MONITOR STRATEGY
| Related DTCs | P050A: Cold start idle air speed control system |
| Required Sensors/Components (Main) | Throttle body with motor assembly |
| Required Sensors/Components (Related) | Engine coolant temperature sensor Mass air flow meter sub-assembly |
| Frequency of Operation | Once per driving cycle |
| Duration | 10 seconds |
| MIL Operation | 2 driving cycles |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
| Monitor runs whenever the following DTCs are not stored | P0010 (Camshaft timing oil control valve) P0011 (VVT system - advance) P0012 (VVT system - retard) P0016 (VVT system - misalignment) P0102, P0103 (Mass air flow meter) P0107, P0108 (Manifold absolute pressure) P0115, P0117, P0118 (Engine coolant temperature sensor) P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle position sensor) P0125 (Insufficient coolant temperature for closed loop fuel control) P014C, P014D, P015A, P015B, P2195, P2196, P2237, P2238, P2239, P2252, P2253 (Air fuel ratio sensor) P0171, P0172 (Fuel system) P0300, P0301, P0302, P0303, P0304 (Misfire) P0335 (Crankshaft position sensor) P0340 (Camshaft position sensor) P0340, P0342, P0343 (VVT sensor) P0351, P0352, P0353, P0354 (Igniter) P0401 (EGR system) P219A, P219C, P219D, P219E, P219F (Air-fuel ratio imbalance) |
| Auxiliary battery voltage | 8 V or higher |
| Time after engine start | 3 seconds or more |
| Starter | Off |
| Engine coolant temperature at engine start | -10°C (14°F) or higher |
| Engine coolant temperature | -10°C (14°F) or higher, and less than 50°C (122°F) |
| Fuel-cut | Off |
| Vehicle speed | Less than 60 km/h (37.5 mph) |
| Atmospheric pressure | 76 kPa(abs) [570 mmHg(abs)] or higher |
TYPICAL MALFUNCTION THRESHOLDS
| Accumulated mass air flow | Less than 60 g (varies with engine coolant temperature) |
CONFIRMATION DRIVING PATTERN
- Connect the Techstream to the DLC3.
- Turn the power switch on (IG) and turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the power switch off and wait for at least 30 seconds.
- Turn the power switch on (IG) and turn the Techstream on.
-
Put the engine in inspection mode (maintenance mode).
Click here
- Start the engine and warm it up for 5 minutes or more.
- Stop the engine.
- Leave the vehicle outside overnight.
- Turn the power switch on (IG) and turn the Techstream on [A].
- Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.
- Check that "Coolant Temp" in the Data List is within the range of -10 to 50°C (14 to 122°F).
-
Put the engine in inspection mode (maintenance mode).
Click here
- Start the engine and warm it up until the coolant temperature is the same as the coolant temperature in the freeze frame data.
- Idle the engine for 1 minute or more [B].
- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
-
Read the pending DTC.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
- Input the DTC: P050A.
-
Check the DTC judgment result.
Techstream Display
Description
NORMAL
ABNORMAL
- DTC judgment completed
- System abnormal
INCOMPLETE
- DTC judgment not completed
- Perform driving pattern after confirming DTC enabling conditions
N/A
- Unable to perform DTC judgment
- Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
HINT:
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows INCOMPLETE or N/A, idle the engine for 3 minutes, let the engine cool down, and then perform steps [A] and [B].
-
If no pending DTC is output, perform a universal trip and check for permanent DTCs.
Click here
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
WIRING DIAGRAM
Refer to DTC P0102.
Click here
CAUTION / NOTICE / HINT
NOTICE:
Inspect the fuses for circuits related to this system before performing the following procedure.
HINT:
Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was moving or stationary, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
PROCEDURE
| 1. | CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P050A) |
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read the DTCs.
Powertrain > Engine and ECT > Trouble Codes| Result | Proceed to |
|---|---|
| DTC P050A is output | A |
| DTC P050A and other DTCs are output | B |
HINT:
If any DTCs other than P050A are output, troubleshoot those DTCs first.
| B | .gif) | GO TO DTC CHART |
|
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| 2. | READ VALUE USING TECHSTREAM (FUEL TRIM) |
HINT:
Calculate the total fuel trim values to check the characteristic deviation of the mass air flow meter sub-assembly.
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Put the engine in inspection mode (maintenance mode).
Click here
| Tester Display |
|---|
| Inspection Mode |
(e) Start the engine.
(f) Enter the following menus: Powertrain / Engine and ECT / Data List / Gas AF Control / Short FT B1S1 and Long FT B1S1.
Powertrain > Engine and ECT > Data List| Tester Display |
|---|
| Short FT B1S1 |
| Long FT B1S1 |
(g) Read the values displayed on the Techstream at engine idle.
(h) Add together the Short FT B1S1 and Long FT B1S1 values to obtain the total fuel trim.
Standard:
The total of the Short FT B1S1 and Long FT B1S1 values is between -20% and 20%.
| NG | | GO TO STEP 7 |
|
| 3. | INSPECT THROTTLE BODY WITH MOTOR ASSEMBLY (THROTTLE VALVE) |
(a) Inspect that there are no deposits around the throttle valve and throttle valve condition.
OK:
No deposits around the throttle valve and throttle valve moves smoothly.
| NG | | GO TO STEP 6 |
|
| 4. | PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION) |
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Put the engine in inspection mode (maintenance mode).
Click here
| Tester Display |
|---|
| Inspection Mode |
(e) Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.
HINT:
The A/C switch and all accessory switches should be off.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / Primary / MAP and Throttle Idle Position.
Powertrain > Engine and ECT > Active Test| Active Test Display |
|---|
| Control the EGR Step Position |
| Data List Display |
|---|
| MAP |
| Throttle Idle Position |
(g) Confirm that the Throttle Idle Position is ON and check the MAP values in the Data List while performing the Active Test.
HINT:
- Do not leave the EGR valve open for 10 seconds or more during the Active Test.
- Be sure to return the EGR valve to step 0 when the Active Test is completed.
- Do not open the EGR valve 30 steps or more during the Active Test.
OK:
MAP change in response to EGR step position when Throttle Idle Position is ON in Data List.
Standard:
| - | EGR Step Position (Active Test) | |
|---|---|---|
| 0 Steps | 0 to 30 Steps | |
| MAP (Data List) | (EGR valve is fully closed) | MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed |
HINT:
- While performing the Active Test, if the increase in the value of MAP is small, the EGR valve assembly may be a malfunctioning.
- Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of MAP may occur while performing the Active Test. However, the amount that the value of MAP increases will be smaller than normal.
| OK | | GO TO STEP 14 |
|
| 5. | INSPECT EGR VALVE ASSEMBLY |
(a) Remove the EGR valve assembly.
Click here
(b) Check if the EGR valve is stuck open.
OK:
EGR valve is tightly closed.
| OK | | GO TO STEP 14 |
| NG | | GO TO STEP 16 |
| 6. | REPAIR OR REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY |
(a) Repair or replace the throttle body with motor assembly.
Click here
HINT:
Perform "Inspection After Repair" after replacing the throttle body with motor assembly.
Click here
| NEXT | | GO TO STEP 20 |
| 7. | CHECK PCV SYSTEM |
(a) Check the PCV hose connections.
Click here
OK:
PCV valve and hose are connected correctly and are not damaged.
| NG | | GO TO STEP 19 |
|
| 8. | CHECK INTAKE SYSTEM |
(a) Check the intake system for vacuum leaks.
Click here
OK:
No leaks from intake system.
| NG | | GO TO STEP 18 |
|
| 9. | CHECK AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY |
(a) Visually check that the air cleaner filter element sub-assembly is not excessively contaminated with dirt or oil.
OK:
The air cleaner filter element sub-assembly is not excessively contaminated with dirt or oil.
| NG | | GO TO STEP 17 |
|
| 10. | PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION) |
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Put the engine in inspection mode (maintenance mode).
Click here
| Tester Display |
|---|
| Inspection Mode |
(e) Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.
HINT:
The A/C switch and all accessory switches should be off.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / Primary / MAP and Throttle Idle Position.
Powertrain > Engine and ECT > Active Test| Active Test Display |
|---|
| Control the EGR Step Position |
| Data List Display |
|---|
| MAP |
| Throttle Idle Position |
(g) Confirm that the Throttle Idle Position is ON and check the MAP values in the Data List while performing the Active Test.
HINT:
- Do not leave the EGR valve open for 10 seconds or more during the Active Test.
- Be sure to return the EGR valve to step 0 when the Active Test is completed.
- Do not open the EGR valve 30 steps or more during the Active Test.
OK:
MAP change in response to EGR step position when Throttle Idle Position is ON in Data List.
Standard:
| - | EGR Step Position (Active Test) | |
|---|---|---|
| 0 Steps | 0 to 30 Steps | |
| MAP (Data List) | (EGR valve is fully closed) | MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed |
HINT:
- While performing the Active Test, if the increase in the value of MAP is small, the EGR valve assembly may be a malfunctioning.
- Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of MAP may occur while performing the Active Test. However, the amount that the value of MAP increases will be smaller than normal.
| OK | | GO TO STEP 12 |
|
| 11. | INSPECT EGR VALVE ASSEMBLY |
(a) Remove the EGR valve assembly.
Click here
(b) Check if the EGR valve is stuck open.
OK:
EGR valve is tightly closed.
| NG | | GO TO STEP 16 |
|
| 12. | PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE VVT LINEAR) |
(a) Operate the VVT system through the Active Test, and check if the VVT system is operating normally.
(1) Perform the Active Test, referring to DTC P0011 Procedure.
Click here
| NG | | GO TO STEP 15 |
|
| 13. | READ VALUE USING TECHSTREAM (MAF) |
Click here
| NG | | GO TO STEP 21 |
|
| 14. | CHECK WHETHER DTC OUTPUT RECURS (DTC P050A) |
NOTICE:
In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Clear the DTCs.
Click here
(e) Turn the power switch off and wait for at least 30 seconds.
(f) Turn the power switch on (IG) and turn the Techstream on.
(g) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.
Powertrain > Engine and ECT > Data List| Tester Display |
|---|
| Coolant Temp |
(h) Check that the engine coolant temperature is between -10 and 50°C (14 and 122°F).
(i) Put the engine in inspection mode (maintenance mode).
Click here
| Tester Display |
|---|
| Inspection Mode |
(j) Start the engine and warm it up until the engine coolant temperature is the same as the engine coolant temperature in the freeze frame data.
(k) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(l) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Powertrain > Engine and ECT > Utility| Tester Display |
|---|
| All Readiness |
(m) Input the DTC: P050A.
(n) Check the DTC judgment result.
| Result | Proceed to |
|---|---|
| NORMAL (DTCs are not output) | A |
| ABNORMAL (DTC P050A is output) | B |
| A | | CHECK FOR INTERMITTENT PROBLEMS |
| B | | GO TO STEP 21 |
| 15. | CHECK AND REPAIR VVT SYSTEM |
(a) Check and repair the VVT system.
HINT:
Refer to DTC P0011 Procedure.
Click here
| NEXT | | GO TO STEP 20 |
| 16. | REPLACE EGR VALVE ASSEMBLY |
(a) Replace the EGR valve assembly.
Click here
HINT:
Perform "Inspection After Repair" after replacing the EGR valve assembly.
Click here
| NEXT | | GO TO STEP 20 |
| 17. | REPLACE AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY |
(a) Replace the air cleaner filter element sub-assembly.
| NEXT | | GO TO STEP 20 |
| 18. | REPAIR OR REPLACE INTAKE SYSTEM |
(a) Repair or replace the intake system.
HINT:
Perform "Inspection After Repair" after repairing or replacing the intake system.
Click here
| NEXT | | GO TO STEP 20 |
| 19. | REPAIR OR REPLACE PCV HOSE |
(a) Repair or replace PCV valve or hose.
|
| 20. | CHECK WHETHER DTC OUTPUT RECURS (DTC P050A) |
NOTICE:
In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Clear the DTCs.
Click here
(e) Turn the power switch off and wait for at least 30 seconds.
(f) Turn the power switch on (IG) and turn the Techstream on.
(g) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.
Powertrain > Engine and ECT > Data List| Tester Display |
|---|
| Coolant Temp |
(h) Check that the engine coolant temperature is between -10 and 50°C (14 and 122°F).
(i) Put the engine in inspection mode (maintenance mode).
Click here
| Tester Display |
|---|
| Inspection Mode |
(j) Start the engine and warm it up until the engine coolant temperature is the same as the engine coolant temperature in the freeze frame data.
(k) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(l) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Powertrain > Engine and ECT > Utility| Tester Display |
|---|
| All Readiness |
(m) Input the DTC: P050A.
(n) Check the DTC judgment result.
| Result | Proceed to |
|---|---|
| NORMAL (DTCs are not output) | A |
| ABNORMAL (DTC P050A is output) | B |
| A | | END |
|
| 21. | CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY CONNECTOR CONNECTION) |
(a) Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter sub-assembly and ECM.
Click here
HINT:
Repair any problems.
|
| 22. | CHECK WHETHER DTC OUTPUT RECURS (DTC P050A) |
NOTICE:
In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Clear the DTCs.
Click here
(e) Turn the power switch off and wait for at least 30 seconds.
(f) Turn the power switch on (IG) and turn the Techstream on.
(g) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.
Powertrain > Engine and ECT > Data List| Tester Display |
|---|
| Coolant Temp |
(h) Check that the engine coolant temperature is between -10 and 50°C (14 and 122°F).
(i) Put the engine in inspection mode (maintenance mode).
Click here
| Tester Display |
|---|
| Inspection Mode |
(j) Start the engine and warm it up until the engine coolant temperature is the same as the engine coolant temperature in the freeze frame data.
(k) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(l) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Powertrain > Engine and ECT > Utility| Tester Display |
|---|
| All Readiness |
(m) Input the DTC: P050A.
(n) Check the DTC judgment result.
| Result | Proceed to |
|---|---|
| ABNORMAL (DTC P050A is output) | A |
| NORMAL (DTCs are not output) | B |
| B | | END |
|
| 23. | CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM) |
Click here
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 24. | REPLACE INTAKE MASS AIR FLOW METER SUB-ASSEMBLY |
(a) Replace the mass air flow meter sub-assembly.
Click here
HINT:
- If the result of the inspection performed in step 13 indicated no problem, proceed to the next step without replacing the mass air flow meter sub-assembly.
-
Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly.
Click here
|
| 25. | CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED |
HINT:
In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Clear the DTCs.
Click here
(e) Turn the power switch off and wait for at least 30 seconds.
(f) Turn the power switch on (IG) and turn the Techstream on.
(g) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.
Powertrain > Engine and ECT > Data List| Tester Display |
|---|
| Coolant Temp |
(h) Check that the engine coolant temperature is between -10 and 50°C (14 and 122°F).
(i) Put the engine in inspection mode (maintenance mode).
Click here
| Tester Display |
|---|
| Inspection Mode |
(j) Start the engine and warm it up until the engine coolant temperature is the same as the engine coolant temperature in the freeze frame data.
(k) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(l) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Powertrain > Engine and ECT > Utility| Tester Display |
|---|
| All Readiness |
(m) Input the DTC: P050A.
(n) Check the DTC judgment result.
| Result | Proceed to |
|---|---|
| NORMAL (DTCs are not output) | A |
| ABNORMAL (DTC P050A is output) | B |
| A | | END |
| B | | REPLACE ECM |
READ NEXT:
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