What causes PCV fails quickly?

Why PCV valve keeps failing?
The last one is a week old - its an Acura part. This can also cause high NO.
Mobile 1 5W30 has been there for 3k miles. Its brownish (dark side) but appears very thin/fluid.

So this and gasoline smell are the ones I am trying to troubleshoot now. Gasoline smell is from the engine compartment but it is probably soon after starting the car and seems to go away. There is no sign of fluid leak in the engine compartment.


Why do you think the PCV valve has failed?

Is gasoline getting into the oil?

Without seeing the readings of all 5 of the exhaust gases under idle and loaded conditions there’s no way to tell what your issue could be, but it almost certainly isn’t the PCV valve.

Here is it.

No idea - no clue

The rattling sound disappeared

Who says it’s the PCV valve?
Excess NOx suggests a clogged EGR passage.
Running lean could do it in theory, but that would show on the O2 number.
Then there’s advanced timing, but does this have an adjustable distributor?

Hmm, high NOx at both speeds. Looks like a weak catalyst to me. There’s no excess O2 departing the exhaust so might be a bit on the rich side but CO is nice and low. Anyway no way a PCV valve is going to fix this.

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Bang on correct.

Based on the 2 earlier posts, both of which concluded the very same diagnosis, this poster is trying their best NOT to replace the failing catalytic converter on this car.

It is time for @scionf to accept the fact that this car is not going to pass smog without a new catalytic converter.


Ah yes, I see those now.

Test report shows the car is not EGR equipped. If ignition timing were advanced I’d expect a higher HC reading. Barring high engine temps or a severely carboned engine, it needs a catalyst.

But maybe Scotty Kilmer has some more nonsense to spout out. :slight_smile:


This car does Not have a EGR valve.

Why that guy is so popular?
I do not mind his videos being 10mins but at times he makes recommendations and does not give adequate warnings (ie Not to do).
Word is he is honest that big corps tried to sue him.

So if I go ahead and change the CAT and the upstream O2 sensor, I am likely pass the emission. But PCV is going bad within a week - I am worried that this is going to come back and bite me.

What I also learned is that CAT is designed for life of the car. If I am changing early, then there is something else causing the CAT to fail early - meaning the replaced CAT will go out in 2yrs or so. The guy who did the SMOG told me that it happened to him.

So this is why the Downstream O2 sensor gives 0.015 volt?
Online readings say that when cruising, it should be around 0.45v.
Could u clarify me?

Also, if its running rich, O2 sensor voltage will be closer to 0.9v, correct? Yes its there on cold start.

You still have not responded to questions about why you think the pcv valve is failing. What is it doing that leads you to that conclusion?


Oh, the rattling sound disappeared - sorry I am tired spending time with the car!
Don’t understand your 2nd question.

Most catalysts last the life of the car. Yours has lasted that long and then some. Your car is 22 years old, far older than average and longer than most people drive cars. It’s beyond its expected lifespan.

Downstream O2 should be mostly stable and flat at cruise. Whether high, low, or in between depends on many factors. Upstream sensor should switch rapidly across .450 volts.


Thank you @asemaster - it helps. So do not worry about PCV valve?

BTW, notable video on 2004 Honda Pilot. He last focused on replacing PCV vale to eliminate CEL. He says other than tune ups, all the parts are original with 285k mileage:

He is talking about resetting the computer by revving at 3k rpm for 5 secs after disconnecting the battery - is this work on my car too or just disconnect the battery would do?

Go ahead, disconnect the battery with the engine running and then go buy a new alternator to replace the one you just fried.

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