Two problems related to battery cable have been reported for the 2008 Chevrolet Impala. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Chevrolet Impala based on all problems reported for the 2008 Impala.
Frequently, service traction control and engine power is reduced lights come on. When this happens, car is sluggish and will not accelerate. This is very dangerous because it happens unexpectedly and causes vehicle to decelerate quickly. Typically the car will start normally after sitting for 15-30 minutes but check engine light remains on for some time. Also, the message engine hot/ac off fires randomly. Temperature gauge rests at zero. It will start working again either through manual reset by removing battery cables and reconnecting or randomly start working again on its own. There are numerous reports of both issues on the internet which indicate replacement of sensors/throttle are very expensive and do not fix the issues.
Car was just started, in parking lot, getting ready to drive and electrical system shutdown completely. Couldn't take key out, or restart, no lights, no electrical activity at all, but it had just been running. After several minutes, it all came back on and restart, and drove ok. There had been battery problems in the past, corrosion on terminal, which was repaired. The battery cable where the wire enters the positive terminal was not completely tight. The internet has reports from several people reporting this same event on Impalas, of several different model years. Most of these though, it happened while they were driving down the road, and some reported accidents that resulted. Prior to all the modern electronics, if the engine was running and the alternator was working, the engine would never just shut down even if the battery connection was bad. This is a very dangerous situation, where the car can just shut off and the operator loses all power systems. No power steering, extremely difficult braking, and the possibility of the steering wheel locking (though the latter did not happen to us). When operating the car in hilly or mountainous roads, where there are steep drop offs on shoulder side, and semi-trucks coming in opposite direction, surely this has potential as deadly situation. Would like to see redundancy, if alternator is producing, don't shut down electrical system. Rather, just give warning. Also, be sure that no car would ever lock the steering wheel when electrical systems malfunction. I am afraid to have my wife drive the car until a new battery cable is installed.