louisice1
Mercedes A Klasse diesel overheating communication fault resolved
Summary of the thread
A 2012 Mercedes A Klasse diesel was experiencing overheating, a check engine light, and coolant leakage, with a 'control unit communication error' detected. The issue was suspected to be related to wiring or connectivity problems affecting the engine control unit (ECU), potentially causing incorrect sensor readings and fan operation. The problem was resolved by identifying and fixing a corroded plug on one of the sensors, which was causing the communication fault.
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4 comment(s)
louisice1 (community.author)
Thanks for the quick response! I haven't specifically checked the ECU wiring itself, I was focusing on the sensors. Where is the ECU located on this model? Is there a specific plug or wire that is a common culprit for these connectivity issues?
linadunkel5
The ECU on your A Klasse is usually located in the engine compartment, often near the battery or behind the front bumper on either side. Unfortunately, there isn't one specific plug known for failing; it's more about corrosion or damage to the wiring harness in general. Given the overheating, the communication fault code, and the coolant loss, it really does point to a potential wiring issue affecting sensor readings. It would be best to get the car to a workshop or experienced technician to inspect the wiring harness thoroughly. Continuing to drive it with an overheating engine could cause further damage.
louisice1 (community.author)
Thanks a lot, I appreciate the help! I took it to a mechanic, who had the same idea. Turns out it was a corroded plug on one of the sensors causing a communication fault. Total cost 95€ including diagnostics. Good call!
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MERCEDES
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AKLASSE
linadunkel5
Control unit communication fault on a 2012 A Klasse diesel sounds familiar. Overheating and coolant spills are textbook symptoms. Have you checked the wiring and plugs connected to the engine control unit itself? A bad connection there could definitely cause a communication breakdown, leading to incorrect fan operation and weird sensor readings. Maybe it's just a connectivity issue. Is the error code specific, can you specify the error code to narrow it down?