Recently had engine MIL come on. Went to Autozone and pulled the code: P0420(inefficient pre-cat on rear bank). Asked for the pre-cat cost - $280/ea. Went home, put in a can of B12 into my gas tank, drove for next 3 fill ups. And presto, the MIL is gone.
I've used B12 for the non-intrusive intake manifold cleaning before and have used it as preventive maintenance two time. This is first time to actually 'fix' a problem.
Coincidence? Maybe. But I'm happy to spend $2.99 vs $280 + labor to replace the pre-cat. YMMV.
