The Ford Obdii Code P139a indicates a problem with the Glow Plug Control Module (GPCM) to Powertrain Control Module (PCM) communication. This code specifically points to an issue with the GPCM output circuit for cylinder 11. While this code might seem technical, understanding its causes, symptoms, and potential solutions can help you address the problem effectively.
Understanding the Glow Plug System in Ford Diesel Engines:
In Ford diesel engines, glow plugs are essential for cold starts. They heat the combustion chamber, allowing the fuel to ignite properly in low temperatures. The GPCM controls the operation of these glow plugs, receiving signals from the PCM. When the P139A code appears, it signifies a breakdown in this communication specifically for cylinder 11. This malfunction can lead to various drivability issues and reduced engine performance.
Possible Causes of P139A:
Several factors can contribute to the P139A code:
- Faulty Glow Plug: A malfunctioning glow plug in cylinder 11 can disrupt the circuit and trigger the code. This is often the most common cause.
- Wiring Issues: Damaged or corroded wiring in the GPCM output circuit for cylinder 11 can interrupt the signal, leading to the P139A code. Wiring harnesses can be susceptible to wear and tear, especially in harsh environments.
- GPCM Malfunction: A defective GPCM can fail to send the correct signals to the PCM, resulting in the diagnostic code. Internal failures within the module itself can disrupt its functionality.
- PCM Issues: While less common, a problem with the PCM itself can also cause communication errors with the GPCM, triggering the P139A code.
Recognizing the Symptoms of P139A:
The P139A code might manifest through several noticeable symptoms:
- Check Engine Light: The illumination of the check engine light is a primary indicator of the P139A code.
- Difficult Cold Starting: Since glow plugs aid in cold starts, a faulty glow plug or related circuit issue can lead to difficulties starting the engine in cold weather.
- Rough Engine Running: The engine might run rough or misfire, especially during cold starts, due to incomplete combustion in cylinder 11.
- Reduced Fuel Efficiency: A malfunctioning glow plug can impact fuel economy due to inefficient combustion.
- Increased Emissions: Problems with the glow plug system can lead to increased exhaust emissions.
Troubleshooting and Solutions for P139A:
Addressing the P139A code requires a systematic approach:
- Diagnostic Scan: Use an OBD-II scanner to confirm the P139A code and check for any other related codes.
- Glow Plug Inspection: Visually inspect the glow plug for cylinder 11 for signs of damage or wear. Test the glow plug resistance using a multimeter.
- Wiring Harness Check: Thoroughly examine the wiring harness connected to the GPCM and the glow plug for cylinder 11 for any breaks, corrosion, or loose connections.
- GPCM Testing: Test the GPCM using a specialized diagnostic tool to determine its functionality.
- PCM Check: If other components check out, the PCM might require testing or reprogramming.
Conclusion:
The Ford OBDII code P139A signifies a problem within the glow plug control system, specifically impacting cylinder 11. Addressing this issue promptly can prevent further engine damage and ensure optimal performance. By understanding the potential causes, symptoms, and troubleshooting steps, you can effectively diagnose and resolve the P139A code, restoring your Ford diesel engine to its proper working order. If you are not comfortable working on your vehicle’s electrical system, consulting a qualified mechanic is recommended.
