Code P0420, catalytic insufficient?

FLOATR925

MEMBER
2001 DODGE DAKOTA
3.9L
V6
2WD
AUTOMATIC
190,000 MILES

What all should I look at with cat code p0420? It seems to not have a lot of power at times, 02 sensor possible. Bank 1? I'm getting a catalytic insufficient. So, I'm not sure this factor it.02 tests show a few saying low on them an 1 says high. The cat tests say normal on some an high on one. Not sure if that's a indication or just what it's measuring but the temperature or use. Sometimes it seems a bit sluggish on acceleration. System tests not codes. On pics See last pic too cat high. But are these readings only showing standings an not meaning there's a problem?

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5 Replies

JACOBANDNICKOLAS

MECHANIC
109,644 POSTS

Hi,

Make sure there are no exhaust leaks before the converter. If there is, fix that first. Next, I attached the diagnostics below for testing. Take a look through them and let me know if you are comfortable performing them.

Also, take a look through this link. It explains how to test it as well. Note there is only one converter on this truck, so that makes it a bit easier.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Let me know what you find.

Joe

See pics below.

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Sunday, September 15th, 2024 AT 7:53 PM

FLOATR925

MEMBER
66 POSTS

Is there an easy method to find exhaust leak?

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Monday, September 16th, 2024 AT 12:51 PM

JACOBANDNICKOLAS

MECHANIC
109,644 POSTS

Hi,

Usually, you will hear it. Oftentimes when it is near the exhaust manifold or at the manifold, it can sound like a ticking.

When you have the engine running, do you notice anything like that? Also, if you can get your hands on an infrared thermometer, it is easy to check if the temps are off at the converter itself.

To check when the engine is at operating temperature, test the inlet and outlet temperatures of the catalytic converter. The outlet should be a good bit hotter due to the chemical reaction taking place in the converter. The outlet should be between 30°F and 100°F hotter.

Let me know if that is something you cand do.

Take care,

Joe

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Monday, September 16th, 2024 AT 7:55 PM

FLOATR925

MEMBER
66 POSTS

I'll have to get a infrared thermometer.
At start up it's a tiny tick but after warm up it's quiet.
Can driveshaft do it also. Or rear bearings?

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Wednesday, September 18th, 2024 AT 11:38 AM

JACOBANDNICKOLAS

MECHANIC
109,644 POSTS

Hi,

When you rev the engine, does the tick get louder and speed up with the engine speed?

Often, a leak at the manifold will go away when the engine warms up because the metal expands.

Let me know. Also, if you could record the sound and upload it for me to hear?

Joe