Understanding OBD2 Code 335

OBD2 code 335 signals an issue with your vehicle’s Exhaust Gas Recirculation (EGR) system, specifically pointing to a problem with the EGR sensor A circuit high voltage. This code is common across various car makes and models, and while it might sound intimidating, understanding what it means and how to address it can save you time, money, and unnecessary worry.

This comprehensive guide delves into the intricacies of OBD2 code 335, equipping you with the knowledge to diagnose and potentially fix the issue. We’ll explore the EGR system, the causes behind this specific code, common symptoms, and the steps you can take to resolve it.

OBD2 scanner displaying code 335

What is OBD2 Code 335?

Your car’s engine management system, often referred to as the ECU (Engine Control Unit), utilizes various sensors to monitor and optimize performance. The OBD2 system acts as the communication bridge, allowing you to access data and diagnose issues through specific codes like 335.

Code 335 specifically indicates that the ECU has detected an abnormally high voltage signal from the EGR sensor A circuit. The EGR system plays a crucial role in reducing harmful NOx emissions by redirecting a portion of exhaust gases back into the intake manifold. This lowers combustion temperatures, which in turn decreases NOx production.

The EGR sensor A is responsible for monitoring the flow or position of the EGR valve, providing critical feedback to the ECU to regulate the amount of gas recirculated. When the sensor’s voltage reading exceeds the predetermined limit, it triggers the check engine light and stores code 335.

Common Causes of OBD2 Code 335

Understanding the potential causes of code 335 is key to effective troubleshooting. Here are some common culprits:

Faulty EGR Valve: A malfunctioning EGR valve, either stuck open or closed, can disrupt the expected voltage readings, leading to code 335.
EGR Sensor Malfunction: The EGR sensor itself might be faulty, sending inaccurate voltage signals to the ECU.
Wiring Issues: Damaged, corroded, or loose wiring within the EGR sensor circuit can disrupt the voltage flow, causing erroneous readings.
Vacuum Leak: Some EGR systems utilize vacuum lines for operation, and a leak in these lines can disrupt the EGR valve’s movement and subsequently the sensor’s readings.
ECU Problems: While less common, a faulty ECU can misinterpret sensor data or fail to regulate the EGR system properly, leading to code 335.

Close-up of EGR valve and sensor

Symptoms of OBD2 Code 335

While the check engine light is a telltale sign, you might experience other symptoms when dealing with OBD2 code 335:

Rough Idle: The engine might experience rough idling due to the disrupted air-fuel mixture caused by an improperly functioning EGR system.
Engine Pinging (Detonation): Pre-ignition or knocking in the engine can occur, often due to high combustion temperatures resulting from a closed or malfunctioning EGR valve.
Increased Emissions: As the EGR system plays a crucial role in reducing emissions, a fault can lead to increased NOx output.
Poor Fuel Economy: A malfunctioning EGR system can disrupt the engine’s optimal air-fuel ratio, potentially leading to reduced fuel efficiency.

How to Diagnose and Fix OBD2 Code 335

Fixing code 335 often requires a systematic approach to identify and address the root cause:

Read the Code: Begin by connecting an OBD2 code reader BMW 335i to your vehicle’s diagnostic port to confirm code 335 and check for any other stored codes that might be related.
Inspect the EGR Valve: Visually examine the EGR valve for any obvious signs of damage, carbon buildup, or blockage. Manually actuating the valve (if possible) can also help identify if it’s stuck.
Check for Vacuum Leaks: If your vehicle’s EGR system utilizes vacuum lines, inspect them for cracks, loose connections, or damage.
Test the EGR Sensor: Using a multimeter, test the EGR sensor’s voltage output against the manufacturer’s specifications. Compare the readings to determine if the sensor is faulty.
Inspect Wiring and Connectors: Carefully examine the wiring harness connected to the EGR valve and sensor for any signs of fraying, corrosion, or damage. Ensure all connectors are secure.
Consult a Professional: If the issue persists after basic troubleshooting, it’s best to consult a qualified mechanic. They have the expertise and equipment for advanced diagnostics and repairs.

“Addressing EGR issues early is crucial,” advises John Miller, a seasoned mechanic with over 20 years of experience. “Ignoring code 335 can lead to more severe engine problems and costly repairs down the line.”

Mechanic inspecting a car engine

Conclusion

OBD2 code 335, while potentially concerning, is a manageable issue when addressed promptly and correctly. By understanding the intricacies of your vehicle’s EGR system and utilizing the information provided in this guide, you can confidently diagnose and potentially fix the problem, ensuring your car runs smoothly and efficiently.

Remember, if you’re unsure about any aspect of the diagnostic or repair process, it’s always best to seek professional assistance from a qualified mechanic. Regular vehicle maintenance and addressing warning signs like OBD2 codes can prevent costly repairs and keep your car operating at its best.