Originally posted by Tony2005:
Originally posted by erb13:
... Your post stated that if the voltage of the downstream O2 sendor were dampened that it was probably not a major problem and just drive it for a while. I am not sure I understand the term "dampened". Do you mean the voltage levels should oscillate at lower levels than the upstream sensor or the switching speed should be slower than the upstream sensor? Or something else.

erb13
98 SVT totally stock


I think what Big Jim means by dampened is "a low switch frequency". Read this TSB (especially Section F3 and figure 5). The switching speed of the lower O2 sensor should be much slower than the upstream sensor for an efficient catalytic converter. When the lower O2 sensor switch frequency gets close to that of the upper O2 sensor, it indicates an inefficient cat.

http://www.v8sho.com/SHO/TSB0197HO2SServiceTips.htm



Good question. Also a good answer.

If the switching rate of the downstream oxygen sensor too closely mirrors the upstream oxygen sensor, the cat isn't doing much and the ineffecient cat code is set.

Did I muddy anything else up here? If there are still questions, please ask.

Jim Johnson 98 SVT 03 Escape Limited