CEL, error code 43, 44 after header install, any ideas?

I had a set of DC headers installed, and reused the o2 sensors. The car ran perfectly before the install, now it hesitates under throttle. Then the CEL came on. I guess the car is supposed to go into run rich mode at that point, but nothing changed. The car didn't pull like it used to; loss of power. It almost felt like I was running lean. I'm sure I'm flowing more air post headers(back of the hand at exhaust tip test). Could the injectors not be able to deliver more fuel? Or is it an o2 sensor problem?

I'm not sure if the mechanic put antisieze on the o2 threads. I've done searches on this topic, and that seems like a possible problem. On my searches for nsx prime header install CEL's, I've seen error codes 41 or 42 (o2 sensor issues) but my searches turned up nothing for 43, 44.

The service manual lists the fuel supply system or o2 sensors as possible culprits. Page 1 I-36 of the service manual says that if 43 or 44 code are accompanied by the CEL and poor drivability, go to page 1 I-86 Fuel Supply System. My poor performance, loss of power points to a new fuel filter, then contaminated fuel, followed by injector....etc. So what do you guys think? Should I:

1. Install new o2 sensors now
2. Wait in hopes of burning off any crap off the existing o2 sensors, or burning off any contaminated gas??
3. Replace the o2 sensors before looking at the injectors or the fuel supply system
4. Just replace the fuel filter

I need help! As always, thank you prime! :smile:

Sam

As I've read somewhere when I was replacing the O2 sensors, do not put anykind of grease to remove the sensors or you will spoil them.

Search is your friend.

The o2 sensors may or may not have anything on the threads, I have not been able to talk to the mechanic yet. Although it seems like that would return a 41, or 42 code not the 43, 44 that I got.

The front and rear 02 sensor wires may be swapped. If so, reverse them and the car will run fine.

After further review of the 43 and 44 codes I am pretty sure the above is what is wrong, your front 02 sensor is telling the rear injectors what to do and vise-versa. Therefore it cannot get the mixture correct.

The problem is that the FRONT 02 sensor harness is in the back of the header, so it is easily plugged into the wrong connector.



HTH,
LarryB

Larry Bastanza said:

The front and rear 02 sensor wires may be swapped. If so, reverse them and the car will run fine.

After further review of the 43 and 44 codes I am pretty sure the above is what is wrong, your front 02 sensor is telling the rear injectors what to do and vise-versa. Therefore it cannot get the mixture correct.

The problem is that the FRONT 02 sensor harness is in the back of the header, so it is easily plugged into the wrong connector.



HTH,
LarryB

Click to expand...

Listen to Larry..I went through exactly what you are experiencing and that's what the problem was. If not I have many new parts for you to try. PM me.

Thanks Larry and m3456y. Update: Looks like #2 was the answer. On my way to see the mechanic, the CEL never came on (first time since install), and the car ran great.

The mechanic told me that he's sure they're plugged in right, he pointed to the fact that the different wire lengths help avoid misplugs. I'm not sure about this, but I am glad the cel is gone and the car runs good. Happy camper.

Jury is still out on the header mod., I'll give it some seat time. Thanks again y'all.

Sam