Catalytic converter replacement

2010 NISSAN MAXIMA

145,000 MILES • 3.5L • V6 • 2WD • AUTOMATIC

RC52

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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?

Aug 3, 2019 at 9:17 AM

KASEKENNY

CERTIFIED EXPERT
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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

Aug 3, 2019 at 9:26 AM

RC52

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Thanks very helpful. Forgot to ask how many catalytic converters on the 2010 Maxima?

Aug 3, 2019 at 2:14 PM

KASEKENNY

CERTIFIED EXPERT
18,907 POSTS

You have two. One coming off the front cylinder head and one on the rear.

I attached the replacement procedure. Let me know if you have other questions. Thanks

Images (Click to enlarge)

Aug 4, 2019 at 2:12 PM