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Forum > General Smog Check > Question

Smog Check Machine Dilution Message

What causes a "dilution" message during the ASM smog test? I work with an ESP analyzer. The Dilution message is right where says low or high RPM on the right side of the screen under the circle timers.

Answer:

A Dilution message indicates excessive oxygen (O2) is entering the smog machine. Either there is a break (vacuum leak) somewhere along the smog machine's (BAR-97 Analyzer) tailpipe probe and hose, or the car you are inspecting has excessive leaks downstream of the catalytic converter. We generally see Dilution problems on older vehicles with rusted exhaust systems. posted by SmogTips Support

You should also make sure your replaceable filters are clean and condensation free. posted by SmogTips Support

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