Unless you were using OEM Nissan sensors I'd bet you still have a bad sensor (possibly a damaged harness or wiring, definitely needs to be inspected thoroughly). This car does NOT play nice with aftermarket sensors, it doesn't help that all the aftermarket ones are junk anyways. If you do need to have the ECU reprogrammed just take it to Nissan, apparently your mechanic charges more than the actual dealership.

 

Sounds funky to me. Ask your mechanic what brand cam sensors he's using. If they're not OE Nissan sensors ($50 a pop) they're well known on these forums to either not work on installation or break again very quickly which sounds like what's happening with you. I could see how a shade-tree mechanic could diagnose the ECM based only off the fact the crappy sensors he's installing keep failing. Those sensors are also very easy to install from the engine bay, pretty sure all you need to do is remove the intake/throttle body which if you have an '04 you should probably clean anyways. Hope he's not charging much to install those.

If there's a better reason for him diagnosing the ECM....
$1000 for an ECM replacement is waaaay too much. I don't know the details but I'm pretty sure it involves unplugging your ECM, grabbing a used one from the same year/model/transmission ($50 on ebay), having it reprogrammed by the dealer, and plugging it back in.

EDIT: Cleric beat me to the punch. But yeah get a new mechanic...

 

Cam sensors require a single 10mm wrench and can be replaced in under 5 minutes per sensor. No disassembly required but it helps if you have small-ish hands.

 

 

What code is it throwing? That's usually a pretty good indicator where to start the diagnosis. If it does turn out to be the ECM it's behind the passenger footwell kick panel, you first need the model number off it then you can source a replacement, it needs to be an EXACT replacement so verify the part number when you buy one. eBay is usually a pretty good source for stuff like that. Then you can drive your vehicle down to Nissan, unplug the battery, swap the ECM which will take all of about 5 minutes if you have the kick panel off already, then they can program the ECM right there in the parking lot.

You will want to call ahead and talk to the service manager to schedule this work though, it should only cost you 1 hour of labor which is like $130 plus the cost of the ECM which is usually under $100 on eBay.

Definitely need to check which diagnostic trouble codes are causing the SES light to turn on though, it might be something simple.

 

 

 

I suspect you have a power delivery problem. I would REMOVE both power cables from the battery and inspect for problems, inspect the fusible link, remove the stereo faceplate assembly and inspect the ECM primary ground that sits right above the stereo.

If those all looked good I'd check the ECM main harness for damaged pins.

Is this vehicle by chance a salvaged title?

You do still have a cam sensor code being thrown and if it wasn't an OEM Nissan sensor I'd replace it after checking everything else.

A lot of those codes can cause other codes, a bad ECU ground can literally cause ALL those codes.

 

 

Yes it absolutely is, is that about the same time you started having problems?