This is a single owner vehicle that we purchased as part of the overseas delivery program. It has received standard factory maintenance along with a series of unfortunate tire replacements (due to my wife’s poor luck with picking up sharp objects on the roadway).
Recently we had an engine overheat issue due to thermostat and fan failure resulting in a burst hose and coolant everywhere. Vehicle was towed to the dealer and repaired.
For some time predating the latest service the key fob range has been significantly diminished. One of two originals keys still worked to start the car in pocket while the other received the “key not found” error unless inserted to start.
About 2 weeks ago, I drove the car locally and parked it. When I returned to the vehicle an hour later, I got the dreaded single click. I tried jumping with my pickup truck. Nothing got it started. I left it overnight in the lot and took to these forums for answers. I had received a variety of errors on the dash including immobilizer so I thought the key fob may needed new batteries. I replaced batteries on both fobs. I returned to the lot the next morning and check the battery voltage as well as the continuity around the fuses on the battery cables. All checked out fine. Guess what!? It started right away like nothing was wrong.
My wife drove it two days later to the same lot, came out about an hour later, and the same issues presented. This time I went with my multimeter and checked everything over. Waited 10 minutes. Inserted her fob into the slot and the car started again.
I started driving this car everyday to commute, instead of my wife. I had no issues for the week. I replaced the TPMS receiver with an EBay find. Instantly better range on the key fobs. However, one still says “key not found” unless its in the slot.
Yesterday I drove home from work (20 minutes). I got changed and went to leave. It would not start. This time the dash dimmed. I broke out the multimeter. The battery was now very low (~5.5v). So, alternator right!? I waited 10-15 minutes, went back out, tested battery and got (~12.5v). Car started. I left it run and tested with alternator running (13.5v to 13.8v). Not ideal. Went on my errands with the vehicle, stopped, started, no problems.
Is it the main battery that needs to be replaced?
I can’t think of anything else and have largely eliminated the other known culprits. The only other thing that I can thing of is that it is some issue with the ignition switch. Trying to avoid going back to the dealer for anything given the vehicle’s age and our plan to replace. Everything else functions great and it still drives like a dream.