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Replacing ECU

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Hellotalkie

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Just got my 04' elantra back from the dealer. He ran a bunch of tests and determined that the ECU is faulty.

I've had the p0340 (camshaft sensor) light on for a while. Installed a new cam and crankshaft sensor and still the engine code will not clear. My mechanic tested the wires and said they're fine. After a couple days of testing it's deemed the ecu is faulty.

I ordered a used ecu for around $75 dollars. Dealer wants 190 to "reprogram"

My question is, do I need to bring it to the dealer at all? Could it theoretically be plug and play? Ohio does not have inspections, or emission inspections.

I read online that some people with 2000 elantra's were able to just plug and play the new ecu in. My key is not chipped. It does have a factory alarm system though
 
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It really depends on the car. Plugging it in shouldn't take you more than a couple minutes.

If people are saying that you don't need to do anything on an Elantra, just plug it in and try to start the car. If it doesn't work, put in the old one and drive to the dealer.
 
cr2250 said:
Most ecu's located above/behind the glovebox?

I'll try this, place is shipping it to me, should be here by end of week.
Click to expand...

Dunno about the elantra but they can just about any where. Under the hood, behind the console, behind the glove box, passenger foot well to name a couple.
 
ECU's are programmed to the car. If your car has any options that the ECU car did not have it could be a problem. For example: If one car had the towing package with a different gear ratio, then the RPM's in the programming will be different for the other car. Always best to take it to the dealer so that it can be programmed correctly.
 
When I was looking to order an ECU, the sites requested the VIN so they could program it for you. Did you pull one from a scrap yard or something?
 
As Bighead said, most ECU replacements will either require your VIN number or the actual ECU program code. On my Mustang, whenever I send out for a new tune, they need to know my ECU program code (which is a 3 or 4 digit number located right on the ECU) which I assume tells them which version of software is on it and some programming parameters.

Is it possibly you are getting a vanilla ECU without any programming on it at all? Therefore requiring the dealership to put a program on it.
 
It all depends on the system they use. For example, the DME that BMW uses also interfaces with several seperate modules, from the radio to the transmission to TPM sensors. The DME knows about these modules via programming.

It all depends on what Hyundai uses. It's possible. You won't mess anything up if it does require some programming. It just won't work. That said, you can try swapping it out and worse comes to worse, you swap the other one back and to go the dealer.
 
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