Mercedes-Benz A35 AMG Has A Check Engine Light

Common Causes for the Check Engine Light in Your Mercedes-Benz A35 AMG and How to Resolve Them

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Reviewed by
Aisha
Written by RepairPal Car Genius
Updated January 14, 2025
0%
40% chance it's the
Emissions System
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60% chance it's
Something else
The most common reasons a Mercedes-Benz A35 AMG has a check engine light are an emissions system component, a sensor, or a catalytic converter.
  • Emissions System: A faulty emissions system component, such as an oxygen sensor or EGR valve, can lead to increased emissions and trigger the check engine light.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a Mercedes-Benz A35 AMG has a check engine light?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

A faulty oxygen sensor is one of the most common causes of a check engine light. Symptoms may include a decrease in fuel mileage, hesitation or misfiring from the engine, rough idling or even stalling. A faulty sensor may cause the vehicle to fail an emissions test.

Any time there is an emissions fault the check engine light will be displayed. The purpose of the check engine light is to inform the driver that an emission related fault has been found, and that there are on-board diagnostic (OBD) trouble codes stored in the powertrain or engine control module. Additionally, since the emissions systems are so intertwined into engine control and transmission control systems, symptoms may include nearly any sort of drivability concerns. This may include harsh shifting, failure to shift, hesitation on acceleration, jerking, engine failure to start or run, loss of power, or any number of other drivability issues.

Due to the nature of electrical systems on modern vehicles, the range of problems these can cause are nearly limitless. However, there is a way to categorize them in two ways. Permanent and intermittent problems. Permanent problems appear and remain. This may be the vehicle will not start, the radio does not work, or the door chime will not turn off among many, many others. These problems are more straight-forward to diagnose since they present themselves at all time. This means there will always be a fault to find. Intermittent electrical problems, however, can be difficult or impossible to locate, since they appear then disappear without warning. The best case scenario for an intermittent issue is when replicating the problem is easily accomplished and understood. This allows a technician to make an issue semi-permanent, allowing them to find the fault. Other issues that come and go without warning and cannot be replicated on demand must occur when the technician is servicing the vehicle, otherwise there is no problem to correct. It is most important to understand that electrical system faults always require inspection, and can include the vehicle working in any manner, or not working at all.

Like we noted in the last section, general diagnosis symptoms are the most vague of the bunch. There are several diagnostic spectrums, electrical diagnosis, drivability diagnostics, engine diagnostics, transmission diagnostics, and the list could continue for about 5 or 10 more spectrums of diagnostics. The most important take-away here, is that general diagnostics are diagnostics that have no other spectrum in which they fit, or the problem is unknown. This means that any vehicle left outside of a repair facility with the keys and an authorization to perform diagnosis will be diagnosed under the general diagnosis spectrum.

When the Check Engine Light comes on, you may experience engine performance issues such as poor acceleration, rough idling, or an engine that won't start. In some cases, no abnormal symptoms will be experienced. Other systems like the transmission or ABS can cause the Check Engine Light to illuminate and lights for those systems can come on at the same time. Similar lights may say "Check Engine Soon", "Malfunction Indicator Light" or just "Check". In rare case the engine can overheat.

Troubleshooting Check Engine Light in a Mercedes-Benz A35 AMG

When faced with a check engine light in your Mercedes-Benz A35 AMG, the first step is to understand the color-coded warning system, as it provides crucial information about the severity of the issue. Begin by using an OBD scanner to diagnose the problem; this tool can reveal error codes that pinpoint the source of the malfunction. Once you have identified the issue, assess whether it can be resolved with a simple repair or if it requires replacing faulty components. Regular maintenance is essential to prevent future problems, so ensure your vehicle is serviced according to the manufacturer's recommendations. If you have addressed the issue and need to reset the check engine light, turn the ignition to the "On" position and follow the specific reset procedure. However, if the light persists or you cannot determine the cause, it may be time to consult a professional mechanic for further assistance. By following this diagnostic approach, you can effectively troubleshoot the check engine light and maintain the performance of your A35 AMG.

What Could Cause the Check Engine Light to Illuminate in a Mercedes-Benz A35 AMG?

When the check engine light comes on in your Mercedes-Benz A35 AMG, it can be a source of concern, but understanding the common problems can help you troubleshoot effectively. One of the simplest issues to check is a loose gas cap, which can disrupt the fuel system's airtightness and trigger the warning light. Another frequent culprit is a defective oxygen sensor, which plays a crucial role in monitoring exhaust emissions; if it malfunctions, it can lead to poor engine performance and increased emissions. Additionally, battery issues, such as a weak or failing battery, can also illuminate the check engine light, indicating that it may need replacement. Other potential causes include faulty spark plugs, which can affect engine ignition, and problems with the catalytic converter, which is essential for reducing harmful emissions. While some of these issues can be addressed through DIY methods, it is advisable to consult with trained technicians for a thorough diagnosis to prevent further complications and ensure your vehicle runs smoothly.

Why is the Check Engine Light in a Mercedes-Benz A35 AMG a Cause for Urgent Attention?

The Check Engine Light in your Mercedes-Benz A35 AMG is not just a simple warning; it is a critical alert that demands immediate attention. When this light illuminates, it signifies that there is a malfunction within the engine or fuel system, which could lead to severe performance issues if ignored. Neglecting this warning can escalate minor problems into major repairs, resulting in significant financial burdens and extended downtime for your vehicle. Moreover, the implications of driving with an unresolved Check Engine Light extend beyond mere inconvenience; they can pose serious safety risks on the road. A malfunctioning engine can lead to unexpected breakdowns or compromised vehicle handling, endangering both the driver and others. By addressing the Check Engine Light promptly, you not only safeguard your vehicle's efficiency and performance but also ensure a safer driving experience. Therefore, it is crucial to take this warning seriously and seek professional diagnostics to identify and resolve any underlying issues as soon as possible.

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