Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Inspection Procedure
HINT:
DTC P050B may be set when the engine has the symptoms listed below. If necessary, check the trouble area listed below.
| Symptom | Factor | Trouble Area |
|---|---|---|
| Low idle speed when engine is cold | Excessive engine friction |
|
| Rough idle when engine is cold | Abnormal combustion | Fuel quality |
- CHECK DTCS
Result:
Any other DTCs are not set.
NG: GO TO DIAGNOSTIC TROUBLE CODE CHART
OK: Go to next step
- READ SHORT-TERM AND LONG-TERM FUEL TRIMS
HINT:
The total of the short-term fuel trim (Short FT) and long-term fuel trim (Long FT) is used to discover a problem in the induction system (between air cleaner and intake manifold).
- Allow the engine to idle.
- Enter the following menus: Powertrain / Engine and ECT / Data List.
- Read the value of Short FT #1 and Long FT #1 (bank 1).
- Read the value of Short FT #2 and Long FT #2 (bank 2).
Result:
Total of Short FT and Long FT is between -20% and 20%
NG: Go to step 4
OK: Go to next step
- CHECK THROTTLE BODY
- Check for deposits around the throttle valve and throttle valve condition.
Result:
No deposits around throttle valve and throttle valve moves smoothly.
NG: Go to step 8
OK: Go to step 9
- CHECK VVT SYSTEM
- Allow the engine to idle with the engine warmed up.
- Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the VVT System (Bank 1) or Control the VVT System (Bank 1).
- Turn on Control the VVT System (Bank 1) (or Control the VVT System (Bank 2)) to advance the valve timing.
- Check the engine condition.
Result:
The engine stalls or idles roughly when Control the VVT System is ON. (VVT system is OK)
NG: Go to step 10
OK: Go to next step
- CHECK PCV SYSTEM
- Allow the engine to idle.
- Pinch the positive crankcase ventilation (PCV) hose.
- Check the engine rpm.
Result:
The engine rpm rises when the PCV hose is pinched.
NG: Go to step 11
OK: Go to next step
- CHECK AIR CLEANER FILTER
- Visually check that the air cleaner filter is not excessively contaminated with dirt or oil.
NG: Go to step 12
OK: Go to next step
- CHECK AIR INDUCTION SYSTEM
- Check the air induction system for vacuum leakage.
NG: Go to step 13
OK: Go to step 14
- REPAIR OR REPLACE THROTTLE BODY
NEXT: Go to step 15
- REPLACE ECM
NEXT: Go to step 15
- CHECK AND REPAIR VVT SYSTEM
NEXT: Go to step 15
- REPAIR OR REPLACE PCV HOSE
NEXT: Go to step 15
- REPLACE AIR CLEANER FILTER
NEXT: Go to step 15
- REPAIR OR REPLACE AIR INDUCTION SYSTEM
NEXT: Go to step 15
- REPLACE MASS AIR FLOW METER
NEXT: Go to step 15
- CHECK DTCS
- Check that the engine coolant temperature is -10 to 50°C (14 to 122°F).
- Clear the DTC.
- Enter the check mode using the Techstream.
- Allow the engine to idle for 1 minute.
- Check that no DTC is present.
NEXT: END
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
