I need to replace the ECU in my '99 because I made a goof and shorted the wires on the #1 fuel injector harness. When I fired it up I heard a loud POP from (probably) the ECU and now that injector will not fire. CEL came up and is giving me a code about the #1 injector circuit something something.

This is embarrassing, but I honestly never noticed this until the other day... it turns out that I have a California emission XJ. I live in PA so I never even considered it. I think what threw me off is that I have the original style exhaust manifold setup with only the two O2 sensors and the single catalytic converter underneath after the front pipe. I had always just assumed that meant it wasn't CA emissions. Oops.

ANYWAY. As everything currently stands at this point other than my current damaged ECU being one for the CA emissions I don't really see anything else that makes it mechanically different to a federal emissions version. I *think* all '99+ came with leak detection pumps standard regardless of emission package.

So what I am wondering is if I am able to get and use a donor ECU from an federal emission '99? They seem to be more abundant/cheaper. Is there any downside or even possibly an upside to doing this? Anything else I should know?

EDIT: Is this legal to do with regards to PA state inspections? The only emissions I would be subject to here are OBD/Gas Cap Test/Visual.

 

California emissions (50-state) uses four o2 sensors and 2 mini cats. This started sometime in 2000 IIRC? Federal emissions (49-state) uses only two o2 sensors and one cat. You need an ECU for Federal emissions based on your description. If you had California emissions, the lack of o2 sensors would have tripped the CEL.

You will need the part number off your current ECU. And if your 99 is equipped with Sentry, you will have to take it to the dealer to have the ECU programmed in order to read the key.

 

Sticker in the firewall says I am CA emissions. My ECU is part number 56041493AE which is for the Cali emissions and my VIN checks out as being low emissions equipped.

But nothing about my XJ is equipped with CA emissions stuff other than my ECU. I think I am just going to try and put a federal emissions ECU for that year on and see what happens! My cat may have at one point been CARB compliant from the factory 17 years ago, but I have no clue. Since I have owned it has always been equipped with a federal cat.

Never had CEL issues or anything. I am so confused.

What is Sentry?

 

I did the ECU swap from my broken 493AE (cali emissions) to the 492AE (federal emissions) and it has been running great. So far no issues and everything I have tested seems to work as well as it ever did.