Error Code P050A is defined as Cold Start Idle Air Control System Performance.
This is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, particularly those made in 1996 up to present. This may include but not limited to vehicle models from Audi, Cadillac, Honda, Hyundai, Kia, Mazda, Nissan, Subaru, Suzuki, Volkswagen, etc. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
When this code is stored, that means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has detected a problem with the IAC (Idle Air Control) system. The term ‘cold start’ refers to engine drivability strategy implemented only when the engine is at (or lower) ambient temperature.
If the PCM cannot control the RPM of the engine effectively during cold start (happens during winter season), Error Code P050A will register, and the Check Engine light will activate. For some vehicles, it may require multiple failures before the Check Engine light illuminates.
Common symptoms of this code include:
- Low or high engine RPM level
- Engine stalls at idle
- Accelerator pedal must be depressed for the engine to start
- Unusual popping or tapping noise from the IAC motor
- Open or shorted circuits or connectors
- Defective or dirty IAC valve
- Defective ECT (electronic coolant temperature) sensor
How to Check
If there are other ECT related codes, it is important to address those problems first before going to the P050A.
Some vehicles will have audible tap or pop noise for this code to store. For Ford vehicles with this code, the problem is most likely caused by a defective IAC.
When diagnosing this code, it is important to refer to vehicle’s information source, diagnostic scanner, and DVOM (digital volt/ohmmeter)
Refer to the vehicle’s information sheet for the specific testing procedures and specifications, connector face views, connector pin-out charts, wiring diagrams, and diagnostic flow charts for the diagnosis.
Conduct a visual inspection of the IAC valve and all of its related wiring and connectors. Look for signs of damages on the wiring harness atop the engine.
Carbon buildup in the IAC valve and seat will cause problems to the valve’s seating. Thus, the valve must be cleaned. Of course, make sure you follow your vehicle’s manufacturer specifications when cleaning the valve.
Set the DVOM at ohms and use it to test the IAC motor. Disconnect the motor from the harness and use the test leads to measure the resistance. If the IAC motor doesn’t comply with specifications, then that means it has gone bad.
If the IAC motor is within specifications, reconnect the IAC motor connector. Probe the input voltage circuit and ground of the IAC connector using the test leads of the DVOM. If the voltage is within manufacturer’s specifications and there is ground, then the fault could be at the IAC valve, or the motor could be defective.
How to Fix
- Repair or replace damaged, open, or shorted connectors, wires, or harness in the IAC
- Clean the IAC valve off of carbon buildup
- Replace IAC motor
- Replace IAC valve
Search through the TSB and look for information that matches the vehicle type, codes, and symptoms you’re experiencing in your vehicle. Often, the manufacturer provides a thorough and comprehensive guide to diagnose and repair for problems like this.