V40 Automatic Transmission Voltage Issue

My 2014 Volvo V40 with a gasoline engine has an automatic transmission issue. The indicator light comes on, and it doesn't shift right, sometimes going into emergency mode. My OBD-II scanner showed voltage-related fault codes, pointing to undervoltage affecting the transmission control module. Could undervoltage cause this?

4 comment(s)

I had similar symptoms with my V40. These transmissions are sensitive. Check your battery and charging system first. Low voltage can cause all sorts of weird issues with the electronics. If the battery and alternator check out, then suspect the transmission itself. I'd suggest a transmission flush.

Did the transmission flush completely resolve the issue, or were other steps needed? Did you also experience the emergency mode? Could worn-out transmission oil cause these errors?

The transmission flush improved the shifting, but the underlying issue was voltage related. I had the emergency mode too. Ultimately, a new battery resolved it. However, it's worth taking it to a workshop to have the error memory read out and the hydraulic fluid checked.

I took the vehicle to a workshop, and undervoltage was indeed the problem. The battery tested okay but was causing fluctuating voltage. A new battery and a transmission oil change costing 240€ seem to have fixed it.

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