What Causes the Secondary Air Injection Malfunction in Mercedes-Benz?
2 Answers
Secondary air injection malfunction. The user needs to replace the air injection driver and the air pump to resolve the issue. This occurs because the power terminals of the air pump are energized, and the internal breakdown of the air injection driver causes the motor power line to remain continuously connected to the 50A fuse, leading to motor burnout due to prolonged operation. Car maintenance precautions: 1. When the engine is hot, never open the radiator cap: otherwise, you may be scalded by splashing coolant or high-temperature steam. After the engine cools down, check that the coolant level is between the full and low marks. If not, add distilled water, purified water, or antifreeze, ensuring the level does not exceed the full mark. If the coolant level drops rapidly in a short time, check the cooling system for leaks or visit a service station for inspection. 2. If the brake fluid level is between the high and low marks, it is normal. If it is near or below the lower limit, there may be a leak or excessive wear of the brake pads, and you should promptly visit a service station for inspection. 3. Check the tire pressure monthly at normal temperature: if it is below the standard, replenish the tire pressure promptly. The pressure should not be too high or too low, as it affects driving safety. 4. A normal spark plug has intact insulation ceramic: no cracks or leakage, and a spark plug gap of 0.8±0.0mm produces a strong blue spark during discharge. If abnormalities are found, adjust the gap or replace the spark plug.
I've seen many Mercedes-Benz owners encounter secondary air pump failures. A common issue is the aging and failure of that small electric motor, especially in vehicles with over 100,000 kilometers. The air pump blades seizing or the motor bearings grinding dry can both cause the pump to stop working. Additionally, the combination valve connected to the exhaust pipe is also prone to problems—if the valve flap gets stuck by carbon deposits, it won't close tightly, and in severe cases, exhaust gas can even backflow into the pump. Remember to check the vacuum lines for leaks; a finger-thick rubber tube aging and cracking can lead to insufficient vacuum. Last time I helped someone troubleshoot an S350, I found the three-way connector was broken—replacing the tube solved the problem.
