I just recently purchased a 1996 Accord with an H22. The car was converted to OBD1. I have a Neptune engine management and B&M fuel pressure regulator. I threw a CEL code 43 this morning on the way to work. Looked up it, fuel system/ oxygen heater. I am just going to start with the obvious (02 sensor) and work my way up through possible culprits (fuel filter, injectors, etc). Here is my question though. The car was tuned in Phoenix, AZ. The car now resides in Bozeman, MT. We are talking, 4500+ feet of elevation change, plus much, much colder temps (20 degrees when I drove through town this morning). Would the elevation change and colder temps cause this code? Colder/less dense air might cause a lean or rich condition. If so, would adjusting the fuel pressure regulator down a bit help at all? Thanks for your help.

-Seth

 

Is your car driving poorly?

If it's driving poorly then check fuel supply related components.

If it's driving okay then check the O2 sensor.

As far as elevation & temperatures being the cause, probably not. I'm not very familar with Neptune so I don't know if you're running open or closed loop. If you're running open loop then the elevation & cold might be a factor.


Modified by 2lude4u at 11:20 AM 11/17/2005

 

Thanks for quick reply. I was assuming it was the 02 sensor, as the car runs great. Would it be wise to replace both 02 sensors, or just the sensor on the exhaust manifold?

I will check with the original owner to see if it is closed loop or open loop. Thanks again.

-Seth

 

I wouldn't run out & replace the O2 sensors yet (unless it's more worth your $/time to simply replace the things). I would check the voltages (mainly for the heater element) for both sensors to determine if one is faulty or it it's wiring.

 

well since you are running obd 1 I think you should only be using one o2 sensor. so you have to figure out which on the computer is looking for. maybe you can just switch the two.

 

That's true, of course make sure that when all is said & done it's using the pre-cat sensor.

 

Adding to the diagnosis...the CEL only comes on when it is really cold out. For instance, when I drive to work in the morning, and when I drive home. If I run errands in the afternoon, it does not come on at all. I'm still thinking its the O2 sensor....

 

yeah, OBD1 only uses one O2 sensor.... I would investigate and see which one is actually being used and remove the other one. That would eliminate one problem.