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Discussion Starter #1
Okay so I bought a 2003 civic for $400 with a blown motor.
Then I bought a d17a from an jdm importer in Chicago.
Engine is installed
I'm using a 2001 civic ex ecu with the ignition and key that matches the ecu.
I am waiting on the vtec oil pressure switch in the mail still. All the wiring is done.
The engine starts and runs but will not go over 4K rpm.
The engine is throwing 2 codes
1. Absent vtec oil pressure switch
2. Bad o2 sensor (I used the ones from the d17a1)

Would not having an vtec oil pressure switch give these results or Am I in limp mode for another reason that wouldn't throw a code that has something to do with the differences between the d17a and a d17a2?

I would think the engine would rev but vtec would just not engage
 

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Install the Vtec switch and reset ECU and try again. It will throw the ECU in limp mode with no switch.

Also the 02 sensors for the EX are different so you may need to match those up to the ECU.
 

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Discussion Starter #4
Okay the vtec issue was resolved with a oil pressure switch. I now am no longer in limp mode.
The issue I have now is with the primary o2 sensor heater code.
First I bought an "upstream" o2 sensor from orielly. it looked like the "down stream" o2 sensor based on how long the wires were but they assured me it was the right one so I took it home. As you know the plugs on the harness are opposite for upstream and down stream so it didn't exactly plug in because it was a "down stream" o2 just as I thought. But out of curiosity of if they were all the same sensor with different wire leg the I made an adaptor harness to be able to plug it in and see if the code would clear. It did not work.

I purchased a new o2 sensor from Napa. The one they had was for the "vtec-e" engine. They had another option for the "vtec" engine but had to be ordered. I told them to order it in cas this one does not work they said it would be in tomorrow morning. The new "vtec-e" o2 sensor did not clear the code. I checked all the wires from the o2 sensor back to the ecu (for the second time) and they all seem good and in the correct spots based on the pin out I am using.

My question is is there really that big of a difference between the different o2 sensors or is my problem possibly ecu related?
 

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Stop just ordering crap that isn't going to fix the problem. Vtec-E is different as it uses a wideband and I think the 03 EX uses narrow band.

Order Denso part# 234-4122 "2003 civic upstream air/fuel sensor EX d17a2"

Denso makes OEM parts for Honda and most Japanese auto makers. I have never had luck with Napa and other 02 sensors.
 

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Discussion Starter #6
Okay I tried the Napa NGK o2 sensor for a 2001 civic ex and it did not work.
Sorry it's faster to just order parts that I can try and return for full refund then wait for replays haha.
I ordered the denso o2 sensor off amazon it will be here Friday.
Thanks for the help.
I'm going to do a load test on all the wires to the ecu tonight.
 

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Discussion Starter #7
Okay I have the denso o2 sensor in of the part number specified. Check engine light is still on. I resistance checked all the wires back to the ecu. There is no power going to black white wire on the plug or at the ecu.
Why would the ecu not be sending power to the heater on the o2 sensor?
So just to clear the air.
100% have a working correct o2 sensor
100% have wired it correctly
Fuse #2 is good.
Have no power to heater wire from ecu.
 

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tumiljones did you ever figure out how to fix the upstream o2 code? I have the same issue after a swap, I've put in a fusible link to the heater wire to make it have 12v. This makes the code clear but then the car idles and drives with erratic missing; I'm thinking because the values for the sensor are either not being read or are thrown off.
 
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