Smog check. fail. lambda

[rede30]

On a 88 325i. I am just a few points too high on HC and NO.

%CO2 is 14 %O2 is .20. CO2 looks normal, o2 is a little higher than I normally get.

I am pulling OA code (lambda). Are my numbers more consistent with intake leaks or O2?

[jlevie]

Could be both. Have a smoke test run and fix the leaks it reveals. The O2 sensor is a scheduled maintenance item with a replacement interval of 100k. If that applies, replace the sensor.

Note that you can't find all of the intake leaks unless a smoke pressure of 2-4psi can be held for at least five minutes. If there are gross leaks that show up immediately, those will have to be fixed and the test repeated until a five minute test at pressure shows no leaks.