Hi All,

This is looking like a pretty common post these days. I have a 92 745T with 165K. I failed the emissions test today with high Non reading at 15 mph. The collected test data is as follows:

MPH rpm %co2 %o2 HChigh HCmeas. CO%high CO%meas. NO(PPM)high NOmeas
15 1657 14.5 .5 114 70 .73 .50 785 1376
25 1725 14.6 .4 88 70 .61 .50 724 721

The tech initially thought it was an EGR valve, but I had him vac test it while running,and the idle became rough as it should. The EGR soenoid is clicking when in the diagnostic mode. He flet that the EGR valve needle was not responding correctly as the idle increased, I don'know if this is true or not. I priced the valve at about $185.00, so I don't want to shot gun this.

I have looked for vac leaks, and have yet to find any. The car does not run hot (needle right in the middle when at temp).

I would like to minimise the cost of this as much as possible. All of the parts that could affect high Nox are pricey.

Any thought based on the above data? I

I have read the FAQs.

Thanks,

Bill