OK, I recently purchased a high-mileage 2004 HCH. (164k) I put a fresh new 12volt battery in, just for safety sake.

The Check Engine and IMA lights come on, codes P1600, P1433. Normal codes meaning a failing IMA battery pack.

I can erase the codes with my OBD1 code reader, or disconnecting the 12volt battery. They don't come back on immediately, sometimes days, sometimes it seems they come on after going over a hard bump, like train tracks.

In any case, the car runs quite normal, Charge, assist, all work fine. Car starts from IMA battery pack. Battery charges and discharges normally. Last drive I made 24 miles urban and freeway, but not over 60 mph, I got 50.1 mpg. for the trip.

Could it be that I just have an intermittant loose connection for the IMA battery pack, that would be causing the lights to come on. I would think if there were a "failure" of some sort, the IMA would not operate as normal?

I bought the car from an independent used car dealer, "as-is", got it for a good price, but have no service records to check, so have no idea if the battery pack has ever been replaced.

 

Well, I guess nobody has any comment!!

 

The only way to know about IMA battery condition would be to do a make a charge-discharge log with some diagnostic tool (like AutoENginuity) and analyze the data.
Because most of the owners don't have access to diagnostic tools it is not possible for them.
The indirect way to diagnose IMA battery health is to watch your fuel economy. If it is low then your battery may not performing well. But it is not 100% accurate way of diagnostics since fuel economy depends on many factors.

 

Well my fuel economy is right where it should be. Close to 50 mpg.

 

I would not worry then.