Aveo Diesel ECU Fault? Troubleshooting Power Loss

Had the exact same problem with my 2017 Sonic diesel (basically Aveo's sister model). Car went into limp mode out of nowhere and engine performance dropped significantly. After some car diagnostics, turned out it was just a faulty main relay affecting the ECU signals. The vehicle electronics were fine, but the relay wasn't providing consistent power. Got it fixed at a workshop, total bill was around 120 for parts and labor. Simple fix but tricky to diagnose without proper tools. What error codes is your Aveo showing? Knowing the specific codes would help determine if you're dealing with the same issue. Also, when exactly does the reduced power mode kick in, during acceleration, at idle, or out of nowhere? I'm somewhat experienced with automotive electronics, but professional diagnosis is best for ECU-related problems since they need specialized equipment to properly test the system.

Thanks for sharing that insight about the relay. My Aveo's at 133180 KM and had its last service about 2 months ago. Getting error codes P0607 and P0638 consistently. The reduced power mode kicks in out of nowhere, sometimes even during normal cruising. Already checked the battery and connections, all good there. The control system seems to be acting up more on cold starts. Interesting that your computer module issue was just down to a relay, definitely worth checking that first before diving into more expensive ECU replacements. Was your throttle response also sluggish before the fix? Mine's really unresponsive when the warning comes on. Would appreciate details on which diagnostic tools your shop used, might help when I take it in.

Yeah, those exact error codes you mentioned (P0607 and P0638) are classic control module communication failures, had them both on my Sonic too. The sluggish throttle response was definitely similar, especially during cold starts. The shop used a professional-grade diagnostic scanner for the system reset and complete ECU testing. They first monitored the voltage supply to the engine control unit while running various tests. When they spotted irregular power delivery, they traced it to that faulty relay. What's interesting is that after fixing the relay, they still had to perform a proper system reset to clear all the stored errors. The computer module needed a complete reboot to start communicating properly again. Without that reset, the car would've probably stayed in reduced power mode even with the new relay. Quick tip: before taking it to the shop, try disconnecting your battery for about 30 minutes. This basic system reset sometimes temporarily fixes the issue and can help confirm if it's an ECU communication problem. If the reduced power mode comes back quickly after this reset, then you're likely dealing with the same relay issue I had. Just make sure the shop thoroughly checks all the vehicle electronics before replacing any major components. A proper diagnosis is worth the initial cost compared to unnecessarily replacing the entire ECU.

Thanks for that detailed breakdown. Just had the battery disconnect reset like you suggested and the car actually ran fine for about an hour before throwing the codes again. This pretty much confirms it's likely a relay issue like you experienced. Called up a local automotive electronics specialist and booked the car in for next week. They'll do a full car diagnostics workup focusing on the control module communication. Mentioned those specific error codes and the intermittent power issues, and they seem quite familiar with the problem. Good call on having them check all vehicle electronics before jumping to ECU replacement, definitely don't want to spend big money if it's just a simple relay causing all this trouble. Will make sure they use proper diagnostic tools to test the power supply and do a complete system reset once they've identified the actual fault. Really helpful to know about your experience with the same symptoms. Will update once I get the official diagnosis back.