Just repaired head gasket...

[RoB51988]

P0420

[LeSabre97mint]

Originally Posted by RoB51988

Haha thats the mistake I made the first time. I just replaced the gaskets thinking it would be alright. Come to find out I get the whole thing back together and 2 days later Im taking it apart again. It cost me 250 go get the head machined and a valve replaced and 50 bucks for the other head to just get surfaced. Really.. when you have this done your supposed to change all valves changed and get new rocker arms depending on your engine. But I was already over budget for having to do it a second time.

Runs like brand new now besides the engine light but thats because antifreeze went through the cat converter and ruined it.

Rob

I think that you need an O2 sensor instead of a cat.

Here is a list of P codes:


P0420 Downstream Oxygen sensor reporting low catalyst efficiency on Bank 1 (Rear Bank)
P0430 Downstream Oxygen sensor reporting low catalyst efficiency on Bank 2 (Front Bank)
These codes are an indication that the catalytic converter indicated is not working properly.
The 2 catalytic converters are part of the "Y" pipe....a single assembly.


Dan

[shorod]

It would certainly be less expensive to start with the O2 sensor than the catalyst, and coolant can damage the sensors. However, it's good that you are prepared to replace the cat as well since that could also be damaged from coolant and the code could be related to that as well.

-Rod

[RoB51988]

Ya I changed the O2 sensor infront of the back cat. Light still comes on so it must be because a/f went through the cat.

[shorod]

You changed sensor 1. The P0420 code, as it would relate to a potential oxygen sensor issue, would be sensor 2 (post converter).

-Rod

[Fordhcw]

When doing the head gaskets it is also a good idea to replace the valve stem seals. Also, the compression of each cylinder should be checked before beginning cylinder head work, so that you know which cylinders have weak compression.