Question about 2000 Mazda MPV
I have a problem with CHECK ENGINE light and the diagnostic shows the fault code P0421. What is it and how to avert ?
Aicux...I had the same problem with a Mitsubishi Montero Sport. The code refers to Warm up Catalytic Converter below threshold (Bank 1) which means the two oxygen sensors before and after the cat closest to the engine are showing a variance that is outside specifications. Bank 1 is on the side of cylinder 1.
I researched and found a cause that was NOT in the list of the usual causes. Generally, this code can be caused by the following:
1 Catalytic converter defective
2 Engine Misfire or similar
3 Large vacuum leak
4 Engine oil leakage into exhaust -valve guide seals, piston rings
I have learned to always look for the simplest solution before paying big bucks for things like catalytic converters, oxygen sensors, etc. I discovered my passengers side manifold was cracked. Took off the heat shield and could see the black residue from exhaust escaping the crack. Got a used manifold from partshotlines.com for $65 and installed it. Reset the code with my OBD-II device and code hasn't returned! Problem solved.
Not sure if this is what's wrong with your, but suggest you chek the simply stuff first. Good luck.
Posted on Sep 26, 2008
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Posted on Jan 02, 2017
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