P050A

What it means

P050A is the generic code for Cold Start Idle Control System Performance. The engine control unit monitors idle speed after a cold start, when it deliberately raises the idle to warm the catalyst quickly. It sets the code when actual idle speed does not match the target it commanded, or the idle control system cannot achieve the target. The exact monitoring strategy and thresholds vary by manufacturer and engine.

Symptoms

• Idle speed too high or too low on a cold start
• Rough or hunting idle until the engine warms up
• Engine stalls or nearly stalls shortly after a cold start
• Hesitation or poor running when pulling away from cold
• Malfunction indicator lamp on
• Hard starting in cold conditions

Possible causes

• Unmetered air leak such as a split intake hose, loose clip, cracked manifold gasket or leaking vacuum pipelikely
• Dirty or sticking throttle body or idle air control valve preventing correct airflow at idlelikely
• Faulty or contaminated mass air flow or manifold pressure sensor giving incorrect load readingspossible
• Faulty coolant temperature sensor causing the control unit to use the wrong cold start idle targetpossible
• Ignition or fuelling fault such as worn spark plugs, weak coils or a leaking or clogged injector causing an unstable idlepossible
• Throttle actuator or throttle position sensor fault, or a throttle body that needs an adaptation relearnpossible
• Wiring or connector damage, or an outdated control unit calibration where the manufacturer has issued an update for this faultrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting coolant temperature, engine speed and load when the code set
2. Check for other related codes such as misfire, lean mixture, air flow or throttle faults, and deal with those first
3. Visually inspect intake hoses, clips, vacuum pipes, the breather system and connectors for splits, looseness or damage
4. Compare live coolant temperature with a true engine temperature on a cold engine to confirm the sensor reads correctly
5. Monitor live idle speed against the target idle, along with air flow or manifold pressure readings and fuel trims, on a cold start
6. Inspect the throttle body for carbon build-up and check the throttle actuator and position sensor readings for smooth, plausible movement
7. Smoke test the intake system to find small air leaks
8. Check spark plugs, coils and injector operation, and check for any applicable manufacturer service bulletins or calibration updates for the model

How to fix

• Repair or replace leaking intake hoses, gaskets or vacuum pipes
• Clean the throttle body and idle control components as the manufacturer specifies, then carry out any required throttle adaptation or relearn
• Replace a faulty coolant temperature, air flow or manifold pressure sensor
• Replace worn spark plugs or faulty coils, and repair or replace faulty injectors
• Repair damaged wiring or connectors, and apply a manufacturer calibration update only where one exists for this fault

Can I keep driving?

Nearby codes

• P0509GenericIdle Air Control System Circuit High
• P050BGenericCold Start Ignition Timing Performance