mammoth713

04z.. P0492

Need smog check this week

Please if someone could clarify, P0492 is the check valve behind block?

Use PBBlaster?

What is downstream from the check valve? Does it literally go to the check valve and then to exhaust manifold?

Just need a fix to pass smog this week

The car usually is fine but once in a while it will show this code. Then I'll reset it and then it will randomly come back

Vetteman Jack

Moved to C5 Tech.

imgn tht

If I recall correctly the P0492 is the passenger side check valve. The wd40 trick *may* work but only short term. I wouldn't trust it to pass emissions. The best fix is to remove the intake manifold and install a new check valve. They are cheap, but I had a hell of a time getting the valve disconnected from the piping with normal hand tools. And there is a bracket behind the manifold that is difficult to work around.

You also may get by with just clearing the code so the CE light goes out, and cross your fingers it stays off long enough to pass through the test which usually only last a few minutes in my state.

Bill Curlee

NOTE!! If you reset the DTC, disconnect the battery, have a weak battery, you will set the EMISSIONS NOT READY FLAGS and will have to put the required numbers of drive cycles on the car before everything resets to EMISSIONS READY.

mammoth713

I finally got around to doing this... I took off the hoses from the driver side T. Plugged the bottom of the t with paper towel, shot pb blaster down into the aluminum t, and then compressed air.

I put it back together and the car is smoking a little on passenger side exhaust..? Is it ok or should I not start the car for a while? Kind of looks like a mixture of a lot of water vapor and a slight hue of black smoke. I'm assuming it's the residual on blaster burning off?

What is downstream from the passenger check valve? Could I have hurt anything? Does the residual pb blaster hurt the cats?

When I was shooting the compressed air it did seem to change sound as if the check valve became unstuck or something

mammoth713

What's interesting is after doing the PB plaster method down the pipe to the check valve, it seems like a lot of water vapor was coming out of the passenger side exhaust. Why would there be so much water vapor? Is it because the valve has been stuck shut and now that it's unstuck, there was a lot of built up condensation behind it that had to clear out?

Here's a photo of how I had the tube before I squirted the PB blaster in it, followed by compressed air. I plugged the bottom hole of the T with wadded paper towel so the air would be directed down toward check valve

mammoth713

I reset the check engine light in the car's computer and drove to work today.. Light came on again on the way home.

Any other ideas? How hard is it to replace this check valve? Should I just have a shop do it?

Is the passenger check valve for sure the issue with this code?

Is it possible something is wrong with the driver's side one causing the computer to think it's the passenger one? What's the part # for these check valves?

Maybe I will try replacing driver's side one

Thanks

runner140*

Some of us have replaced the drivers side check valve, relocated the check valve (secondary) on the pass. side THEN, removed the entire system.....smiles. Twenty feet of hose, two block off plates. The air pump and a cap off of the vacuum hose/cap the intake hole. Two check valves.. and reprogram. That's about it.

mammoth713

That's not an option since I'm in CA

C5MSG2004Vert

See this thread. He lives in California and just turned things off.

v6turbo87

Its the passenger side valve and replacing the driver's side will not make the code go away. The right way to fix it is to remove the intake manifold and replace the valve. May as well replace the oil pressure sending unit while the intake is off as that is a high failure item as well.

royal flush

Take to a tuner--TUNE OUT--problem gone forever-