Revised posting: I started this thread in the belief that a bad battery was causing my MIL (check engine light) to come on occasionally. Replacing the battery seemed to solve the problem, briefly, but then the problem returned and I began experiencing running problems (cutting out at higher speeds.) If you read through this thread, you'll see that I considered that perhaps the fuel injection system was going into a "limp mode" and was preparing to chase down an FI problem. Before doing so, however, I replaced the spark plug caps, and it turns out that a bad cap may have been the culprit all along. With new NGK caps, both the MIL and the poor running problems seemed to have cleared up. (I am not entirely clear why bad caps would trigger the MIL, but the caps seem to be the cause of my problems with running at higher RPMs.) Posts in this thread from other forum members have good information on reading MIL codes and other useful comments. But I caution anyone reading this thread that my own theories as I tried fixing this problem on my own (bad battery, FI problem) may have been red herrings.
(From initial post) My check engine light was coming on occasionally, no other problem with the NT. Sometimes it stayed on after starting (rather than going off within about 3 seconds), sometimes it came on during highway riding and stayed on. Then it might stay off for a week or more.
I ran voltage checks on the battery. Even after reaching a "green" indicator on a battery tender, the battery voltage (engine off) was below spec. Good voltage with engine on, so I concluded the charging system was OK.
I installed a new battery a couple of week ago and have had no check engine light problems since then.
By the way, in the NT the battery is laid on its side. This shouldn't be an issue as the battery is sealed. But the NT battery connections fit on the battery terminals from the side rather than over the top. I had to hacksaw off about 1/16 of an inch from the NT's positive battery lead to get it to fit the aftermarket battery I bought. No real problem with this, just a minor adjustment.
(From initial post) My check engine light was coming on occasionally, no other problem with the NT. Sometimes it stayed on after starting (rather than going off within about 3 seconds), sometimes it came on during highway riding and stayed on. Then it might stay off for a week or more.
I ran voltage checks on the battery. Even after reaching a "green" indicator on a battery tender, the battery voltage (engine off) was below spec. Good voltage with engine on, so I concluded the charging system was OK.
I installed a new battery a couple of week ago and have had no check engine light problems since then.
By the way, in the NT the battery is laid on its side. This shouldn't be an issue as the battery is sealed. But the NT battery connections fit on the battery terminals from the side rather than over the top. I had to hacksaw off about 1/16 of an inch from the NT's positive battery lead to get it to fit the aftermarket battery I bought. No real problem with this, just a minor adjustment.
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