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Ok so I'm new to this and I have no clue about cars but I thought I'd give it a shot to ask.

So I recently got my engine rebuilt on my 2001 Honda Civic LX automatic. I had to get a whole new cylinder head because there was a hole in one.

It was a D17A1 engine, it now says D17A2, I know the mechanics had to change the shortblock but I don't know the difference between short or long block.

Can you use a D17A2 to replace a D17A1? Will this throw codes on my MIL/CEL?

I recently started getting a P0420 but I don't know if this could be causing it because it never threw that code before. I am a girl and don't want to be taken advantage of when working with mechanics. Just want to know if this could be causing my CEL to throw faulty codes.

Thanks I know my question sounds dumb.

 
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Yes you can swap the 2 engines but it requires the exhaust to be modified and the ECU. That code could be an indication that something was not installed properly.

 
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Thank you, I doubt they modified it. Is it hard to modify the ecu?

They used the same cat that is attached to the exhaust manifold, it isn't located under my car, it is under my hood.

I know that D17A2 is vtec and the cats for those are located under the car.
Could this be another reason for my car not running great? It's slow into first gear and I have a rebuilt transmission as well.

Sorry for all the question, iI'm just not good with cars.

 
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you need to swap in a ECU for that specific engine. no modifications, just install and have the wiring installed in the VTEC solenoid.
get a 01-02 ECU, 03+ (or was 04+?) requires wideband o2 sensors and they are pricey as h3ll

edit: just realized how contradictory my post was... :P first sentence sounded wrong, i meant for a VTEC engine vs a non-VTEC. the years will not matter, but a wideband sensor year car will throw codes if run with a narrowband sensor that is standard in 01/02 cars. not sure of the 03. o2 narrowband is 50-ish, wideband is 250+...

 
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I was thinking modify as with the VAFC. Getting the correct ECU would be best.

Maybe they used a different year ECU that crossed over to the wide/narrow band o2 sensor change and that is causing the code.

You should be able run an Ex engine with Lx exhaust setup since it works the other way around.

 
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yup, understood, but i heard it is hard now to find the VAFC?

 
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So what you guys are saying is that they need to install a new ecu to modify the vtec engine? Or they need to modify the exhaust?

I am going to go tomorrow to let them know and I just want to make sure I have all my facts straight.

The p0420 is Catalyst System Efficiency Below Threshold (Bank 1)

I just know that vtecs have cat under car, and mine is under the hood. So that is basically what is wrong with the car? Correct?

Lol. Sorry for the repetition of questions, just want to go in knowing what I'm talking about because I don't want them to take advantage and give me the run around.

 
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Yeah, both those guys got a little wordy there...

They are saying when the engine was changed the ECU should have been changed with it. The 2 engines use different types of O2 sensors and this may be the source of your problem..

As well, you should edit the title of the question because it's confusing 'D17A1/D17A1" should be 'D17A1 swapped to a D17A2'.

just sayin'

 
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Thank you I just wanted to get that cleared up

Now I know what to say tomorrow when I go get it fixed.

on another note, I don't know how to change the title of the post. I noticed that after I had already hit submit.

 
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just go to your first post and push the 'edit' button then 'go advanced'

 
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There are different ex ecu's that are available. '04-05 use the wideband o2 sensors. I've got an a2 in my dx and have been running it with the original ecu and a1 wiring harness for 2 yrs with no issues. I have the vafc2 I installed for vtec. My exhaust is original except for a header with an o2 Defouler for the codes