Fix P050A: Mechanic’s solutions that WORKED

The P050A: Cold Start Idle Air Control System Performance code is triggered when there is an issue with the performance of the idle air control system during a cold start. This system is crucial for maintaining a stable and efficient engine idle immediately after the engine starts, especially when it’s cold. The code suggests that the engine is not idling as expected, which could be due to various reasons like a dirty throttle body, issues with the idle air control system, or even software problems in the engine’s control unit.

P050A quick overview

Meaning	P050A: Cold Start Idle Air Control System Performance
Is it serious?	This code is not typically serious but can affect engine performance, especially during cold starts.
Possible causes	– Dirty or malfunctioning throttle body – Faulty idle air control system – Issues with the Positive Crankcase Ventilation (PCV) system – Software issues in the Engine Control Module (ECM) – Air intake leaks – Faulty engine sensors affecting idle control
How to diagnose?	Inspect Throttle Body: Check for cleanliness and proper operation. Evaluate Idle Air Control System: Assess its functionality and look for any malfunctions. Check PCV System: Inspect for any leaks or issues. Review ECM Software: Verify if there are any updates or reprogramming needed for the ECM. Search for Air Intake Leaks: Use a smoke machine or similar method to find any leaks in the air intake system. Test Related Sensors: Ensure sensors like the Mass Air Flow (MAF) and throttle position sensors are functioning correctly.

How to fix P050A – learn from mechanics

I looked into P050A service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Kia

Vehicle Information: 2015 Kia Soul 1.6L

Issue + Repair History:

• MIL lamp on with rough idle and hesitation.
• Retrieved code P050A.
• Replaced weak battery, cleaned throttle body, performed induction service, replaced plugs due to carbon deposits.
• Idle improved and hesitation resolved, but vehicle returned with the same code and no running issues.
• Swapped throttle body with a known good one, checked throttle body pins, reset adaptive values, cleared codes.
• Vehicle returned again with the same code P050A.

Related Repair History:

• Unknown

Computer Codes & Descriptions:

• P050A: Cold start idle air control system

Other Test Results:

• DTC: P050A
• Fuel pressure: 73 PSI on low side at idle
• Vacuum: Steady at 18 in

Suggestions to Fix Issue:

• Software glitch in the PCM identified as a likely cause.
• Recommendation to wait for a software update from Kia as a resolution.
• Suggestion to check if there’s a TSB involving ECM reprogramming.

Final Fix:

• Awaiting software patch from Kia, as the issue is related to a software glitch in the PCM.

Case #2: Audi

Vehicle Information: 2009 Audi A4 Quattro 2.0L

Issue + Repair History:

• Initially came in with codes P0302, P0304, P2279, and P2188. Issue not duplicated; smoke checked intake (no leaks), purge valve tested fine.
• Plugs and coils replaced, all readiness set, but problem recurred.
• Additional codes on return: P2271, P052A, P050B, P2178, P0506, P050A, P0301, P0303.
• Freeze frame data showed two different sets of codes/mileage records.
• Fuel trim: 9% LT and -9% ST at idle.
• No excessive vacuum in the crankcase.
• ECM connections checked; all okay.

Related Repair History:

• Replaced plugs and coils.

Computer Codes & Descriptions:

• P2279: Leak in air intake system
• P2271: O2 B1S2 too rich
• P052A: Cam adj. B1 intake
• P050B: Cold start ign timing performance
• P2178: System too rich off idle
• P0506: Rpm lower than expected

Suggestions to Fix Issue:

• Checking the PCV breather (crankcase breather) as a potential cause.
• Verifying camshaft timing and tensioners.
• Considering replacing the intake manifold if it has internal issues (like broken flaps).
• Exploring the possibility of a fuel injector issue or high-pressure fuel pump issue.

Final Fix:

• Replaced the OEM breather and the intake manifold due to broken flaps causing a large vacuum leak.
• The manifold issue was a new development, while the PCV breather was suspected to be the intermittent problem. The cam code has not returned.

Case #3: Volkswagen

Vehicle Information: 2012 Volkswagen Passat SEL Premium 3.6L

Issue + Repair History:

• Vehicle arrived with rough idle, hard starting, and check engine light on.
• Numerous codes present: P1913, P0100, P0102, P050A, P0113, P0300, P0301, P0302, P0304, P0130A, P0150A.
• Compression test showed good results.
• Replaced MAF sensor, cleaned fuel injection system.
• Still experiencing misfires on cylinders 1, 2, 3.
• Fuel pressure fluctuating between 20-60 psi at idle.
• Spark plugs on cylinders 1, 2, 3 appeared very rich.

Related Repair History:

• Replaced MAF sensor.
• Cleaned fuel injection system with Motorvac.

Computer Codes & Descriptions:

• P0300 – P0300, P0301, P0302, P0303 (Misfires on cylinders 1, 2, 3)
• P050A – Cold start idle air control

Suggestions to Fix Issue:

• Check PCV for internal air leak.
• Scope ignition and injector waveforms.
• Check if the system has a high-pressure fuel pump.
• Consider cleaning or reprogramming the throttle body.
• Flow test fuel injectors and check fuel pressure.
• Check the crankcase breather, which is part of the valve cover.

Final Fix:

• The problem was a broken exhaust valve spring on cylinder 3.
• After replacing the valve spring, the vehicle ran like new.
• Compression test initially showed 155 psi, but the issue was detected upon further inspection.

Case #4: Subaru

Vehicle Information: 2012 Subaru Legacy 2.5i Premium 2.5L

Issue + Repair History:

• Vehicle arrived via tow truck with very rough idle and multiple misfires.
• Codes: P0301, P0303, P0304, P050A, C0231, C110.
• Replaced spark plugs, misfires resolved on cylinders 3 and 4, but cylinder 1 still misfiring.
• Swapped coils and fuel injectors between cylinders 1 and 3, but cylinder 1 still misfiring.
• Fuel trims under 5%, no lean codes.
• Timing and EGR considered as possible issues but no related codes.

Other OBD2 Codes + Test Results:

• Compression test: Cylinder 1 at 90 psi dry, 150 psi wet, other cylinders around 150-160 psi.
• Checked spark on all cylinders – good spark.
• Timing covers pulled, engine turned over multiple times, timing remained perfect.

Suggestions to Fix Issue:

• Retest low compression in cylinder 1.
• Perform cylinder leak down test.
• Check oil level and quality.
• Check fuel quality and throttle body condition.
• Consider possible timing belt issue or valve guide problems.
• Check for any potential ECU related issues or fuel injector problems.

Final Fix:

• Conducted a top engine clean for about two hours.
• All misfires cleared and the vehicle now runs perfectly.
• The exact reason for how the top engine clean resolved the issue remains unclear.

Case #5: Ford

Vehicle Information: 2006 Ford Fusion SE 3.0L

Issue + Repair History:

• Customer reported car died suddenly while driving, resembling a key-off situation.
• On arrival, the car was a crank/no-start condition.
• Found ignition coil fuse blown; replacing the fuse immediately blew it again.
• Discovered two rear head ignition coils had exploded, emitting a bad smell.
• After coil replacement, the fuse still blew.
• Codes present: P0351, P0353, P0355, P0356, P050B.

Other OBD2 Codes + Test Results:

• Checked coil pack wires for shorts, initially found none with ECM disconnected.
• On reconnection, shorts were detected in two coil wires.

Suggestions to Fix Issue:

• Check all coil control wires with an ohmmeter for a short to ground, with both processor and coils disconnected.
• Disconnect all coils to see if the fuse still blows to rule out coils as the problem.
• Investigate the possibility of an ECM issue due to direct short detection.

Final Fix:

• The issue was a dead short in the ECM.
• Short detected in two coil wires when ECM was reconnected.
• Replaced ECM which resolved the issue.

Advice	Diagnostic Step
Check PCV System	Inspect the Positive Crankcase Ventilation (PCV) system for leaks or malfunctions.
Inspect Throttle Body	Clean the throttle body and check for proper operation, including the idle air control system.
Perform Software Update	Verify if there are any software updates available for the vehicle’s ECM and apply them if necessary.
Check Fuel Quality	Inspect the fuel quality, including for potential contamination or use of incorrect fuel type.
Evaluate Engine Valves	Examine the engine valves for issues, including valve springs and guides.
Analyze Fuel Trims	Review the vehicle’s fuel trims for indications of lean or rich conditions that might affect idle air control.