The Most Common Car Diagnostic Codes on Volkswagen Vehicles and What Can Cause Them

Check Engine Light On?

Nearly every car owner can understand the stress that accompanies the check engine light. The car seems to be running fine until that orange engine in the middle of the dash suddenly lights up. However, for Volkswagen owners, the check engine light (or the Malfunction Indicator Light) can cause even more anxiety due to the difficulty of finding a reputable auto repair shop that specializes in repairing and maintaining imported vehicles.

When a Volkswagen’s check engine light turns on, it means that the vehicle has at least one On-Board Diagnostics (OBD-II) trouble code. While some vehicles can display the OBD-II trouble code on the dashboard, many older VW cars don’t have that capability. Most auto part stores can perform a free plug-in diagnosis with an OBD scanner. However, the readout of the OBD-II trouble code is only the beginning of diagnosing and fixing a problem with a Volkswagen vehicle. While OBD-II codes can be useful, it’s important to remember that a trained diagnostic technician should investigate and analyze the problem because multiple issues can cause OBD-II trouble codes.

EVAP System Leaks

Don’t worry. The check engine light is not always a sign of doom for a beloved VW. In fact, the most common diagnostic code for Volkswagen vehicles is caused by a loose gas cap. The OBD-II trouble code P0457 is an indication of a problem with the vehicle’s EVAP system. Often, this problem because of a loose or malfunctioning gas cap. The gas cap’s seal can degrade or crack after continued use which can result in an improper fuel tank seal. Sometimes the cap needs to be tightened, but it also may need to be replaced entirely. If replacing the gas cap does not reset the check engine light after a few driving cycles, the EVAP system needs to be inspected by a trained Volkswagen technician.

Ignition Coil Malfunctions

Another typical OBD-II code readout for Volkswagen vehicles indicates an issue with either the car’s ignition coils. Many trouble codes can indicate a problem with the car’s ignition coils. These include trouble codes P0300, P0301, and P0302. Many Volkswagen four-cylinder engines, most often the 1.8T and 2.0T, have issues with their ignition coils. Sometimes a brand new ignition coil will fail before 10,000 miles. If the car’s check engine light is flashing and the engine is shaking, at least one of the ignition coils may need replacing.

Oxygen Sensor Failures

Oxygen sensor failures are not a problem unique to VW vehicles; it’s common for an oxygen sensor to fail between 80,000 and 100,000 miles. OBD-II trouble code P0130 is a result of the Engine Control Module (ECM) failing to detect any activity from the oxygen sensor. If the check engine light is on, the car stalls frequently, or excessive amounts of smoke come from the exhaust, the oxygen sensor may be malfunctioning or failing. While frayed wiring or corrosion is the most likely cause of a problem with a Volkswagen’s oxygen sensor, the ECM may be malfunctioning as well.

Worn Spark Plugs

Most VW vehicles need to have their spark plugs changed around the 90,000-mile mark. If this maintenance is not taken care of on time, the check engine light will come on after 120,000 miles. The OBD-II trouble code P0303 indicates a misfire in the #3 cylinder in Volkswagen cars. Most likely, this is because of worn-out spark plugs, but other problems can trigger code P0303. These include worn-out ignition wires, low fuel pressure, or a defective mass airflow sensor. It is best to have a reputable auto repair shop that specializes in imported or VW vehicles diagnose and analyze the issue if changing the spark plugs does not get rid of the OBD-II code after a couple of driving cycles.

Coolant Temperature Sensor Failures

Volkswagen vehicles are known for their dependability, but the coolant temperature sensors commonly need replacing after extended wear. The OBD-II trouble code P2184 indicates that the ECM detects an issue with the car’s coolant temperature sensors. Most often, the only symptom of this problem is the check engine light. Replacing the coolant temperature sensor is a low-cost, easy DIY repair for a home mechanic. However, replacing the coolant temperature sensor and the associated wiring may not reset the check engine light after a few driving cycles. A malfunctioning coolant temperature sensor can cause a vehicle to fail its emissions test. If this is the case, it is important to take the vehicle to an auto repair shop staffed with trained VW technicians.

Check Engine Light Always On

If the check engine light is always on or is flashing in a Volkswagen vehicle, this can indicate numerous issues with the car’s performance. Don’t ignore a check engine light for long, and don’t drive for an extended period if the check engine light is flashing. A flashing check engine light can indicate abnormal combustion. Continued use of the car can have devastating effects on the VW’s engine. Additionally, if the check engine light is on, but the driver display does not present any OBD-II trouble codes, this may mean that the OBD-II code is specific to Volkswagen vehicles and diagnosis by specialized scanning tools is necessary.

Trained VW Technicians

Volkswagen vehicles can last decades with regular maintenance and care. The easiest way to diagnose and fix the cause of a VW’s check engine light is to take the vehicle into a specialized auto repair and maintenance shop. Steve’s Imports in Portland, Oregon was originally called “Steve’s VW” in 1974. Steve’s Imports employs passionate technicians with decades of combined VW experience. The technicians at Steve’s Imports have access to advanced diagnostic tools and scanners to help diagnose and fix that pesky check engine light.