matteoblaze1
SM3 Reduced Engine Power
Summary of the thread
A 2019 Renault SM3 experienced significantly reduced engine power, suspected to be due to a defective engine control unit (ECU). Another individual with a similar issue suggested checking the main relay for the ECU, as it is known to cause such problems. Upon inspection, the main relay was found to be defective, and replacing it resolved the power issue.
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4 comment(s)
matteoblaze1 (community.author)
Could you elaborate on the symptoms you experienced and whether the error stored in the error memory was the same? Also, what did the diagnostics report in terms of the error code?
jakobmeier1
Yeah, man, it was rough. Basically, the car felt like it was running on two cylinders sometimes. Super sluggish acceleration, and the check engine light was on constantly. I don't remember the exact error code, but it pointed towards ECU issues. A new main relay fixed it right up. Honestly, with those symptoms, I'd just take it to a reputable workshop. They can pinpoint it and get you sorted.
matteoblaze1 (community.author)
Following your suggestion, I had the main relay checked, and it was indeed defective. Replacing it resolved the issue, with a total repair cost of 120€.
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RENAULT
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SM3
jakobmeier1
Dude, I had something similar happen in my SM3! I was getting seriously limp-mode vibes. Error codes all over the place. I bet it's the main relay for the ECU. Those things are notorious for crapping out and causing all sorts of weirdness. Check that first!