I’ve had low fob battery warnings in both my HHR’s and simply replaced the battery, both were OEM fob’s.

 

True, the car's computer is programmed to accept the fob. And if it were not programmed, you would not get any message at all on the DIC, nor would the OP be able to unlock the doors.

I had 3 consecutive Dorman fobs that the computer had been programmed to accept. Each one worked fine, except for the "low fob batt" message on the DIC. Didn't matter how many brand new, tested, fob batteries I tried. The solution was to get an OE fob.

 

As I've done quite a few of these HHRs on this problem (with all successes) the owner's manual does not explain anything on this problem .....its minor info..........
Disconnecting the battery for 30 minutes or touching the positive to the negative does not solve this problem.... It is in the remote..... The remote has a memory of the last battery that it had in it..... Which it sends to the onboard computer...And its the FOB that tells the computer that info about the battery...not vice versa......the DIC only displays that info...nothing else...it has NO control over the voltage out of the battery in the FOB.......the FOB does...it sends its signal to the computer.... And if the last battery was low....it's going to say that on the DIC.....Sooo...you can put 35 new batteries in that remote FOB... And it will still say Fob low battery on the DIC....must reprogram..... Once you install the new battery... which you should check it with an ohm meter first....... You should read 3.3 volts on the battery..... Insert the battery back in and follow your reprogramming instructions for your FOB
VOILA...Success!!!

 

Happy it works for you. According to Energizer batteries you should see 3.0 volts

 

And what method do you use to reprogram?

 

If you are talking about 2008 models, the RCDLR does need to get updated firmware if the battery in the car has been dead. That applies only to 2008, and mostly to the TPMS. There is a TSB on the subject. I would think there would be one about the low fob battery, there are TSBs about much less important things.

 

I just did another one today.....Voila!! SUCCESS........ this one was with a Dorman..........each FOB has specific details on how to program it to the car....follow those instructions... Battery HAS TO BE at least 3.3v standard 3v battery to remove the message...if it has 2.9v you will still get the message