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93-525i
10-03-2005, 08:48 AM
Hey all,

I wanted to find out what the bolt on top of each of the exhaust manifolds are for? The is one bolt per manifold and it sits right on top. Any ideas?

Thank
Bill R.
10-03-2005, 08:57 AM
Its for a probe that you can insert to monitor CO and HC levels before the catalytic converter, it can also be used to measure exhaust back pressure.
Jon K
10-03-2005, 10:37 AM
Its for a probe that you can insert to monitor CO and HC levels before the catalytic converter, it can also be used to measure exhaust back pressure.


Or EGT :)