Catalytic converter replacement

RC52

MEMBER
2010 NISSAN MAXIMA
3.5L
V6
2WD
AUTOMATIC
145,000 MILES

I recently blew a head gasket. Replaced the engine but apparently ran a lot of coolant/water through the system and by extension the catalytic converters. The mechanic who did the motor swap indicated the check engine light was because of bad catalytic converters. He indicated all would need to be replaced. I know unburnt fuel can cause cat failure. Would coolant/water have the same effect?

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Hi,

So unburned fuel will break down the catalyst inside the converter that is responsible converting harmful emissions to non harmful. This causes it to be "hallow" and not efficient. When oil, coolant, and water go through the converter it actually clogs it up and causes it to be less efficient and set the light. So if you have a code for catalytic converter inefficiency then more than likely it is clogged or restricted.

If you are replacing that, I would just go ahead and put new o2 sensors in it as well. You are there and it is not much more to just renew it all at the same time because what ever went through the converter also past by the sensors and the tips can get clogged as well.

Let me know if you have more questions. Thanks