I replaced my PCV system this weekend. Repair went according to plan and car started up and ran fine for 40 plus miles, a mixture of highway and city driving.

Had the oil and filter changed this afternoon.

The CE light went on this evening after a short trip. Put it on the OBD checker and it’s showing a stored P0133 (O2 sensor Circut Slow response) and a pending P0422 (main catalyst efficiency below threshold).

My assumption was that all the shaking around of components under the hood this weekend could have damaged a connection somewhere, not sure. Sounds like maybe my cat is backing up? Is it normal for a car with a fresh PCV to throw some codes after overhaul?

Not sure what the difference between a pending and stored code is either. Anyway, if anyone has any thoughts on this please share. Interestingly, the car is no longer throwing the Evap Leak code that it always used to throw pre-PCV replacement. Thanks.

 

There is no connection between your PCV service and the code. The P0422 says that the catalytic converter is not doing its job effectively.

My suggestion would be to clear the codes and start over. See if the code returns and then deal with it.

 

Right but couldn't that be because of clearing all the ports and maybe some lodged in crud finally broke loose and shot out of the motor and into the cat in conjunction with the repair and the Gumout cleaner being used?

I did clear the codes. We will see what comes back. What do you make of the P0133 O2 Sensor current low code? Could that be related? I just find it odd that they both occurred two days after a major repair.

 

Any type of "crud" that gets into the converter will typically burn off unless it is totally saturated with some type of residue. You can have contamination from coolant but in your case, I would wait and see.

Code P0133 says that the oxygen sensor is not responding very fast to the changes in voltage that go along with the fuel mixture. If you continue to see that code, change the oxygen sensor.

In your case this code points to the first oxygen sensor in the stream.

 

To add to tony1963, the P0422 measures cat efficiency by comparing the signal from the front O2 sensor to the signal from the rear 02 sensor. It seems to reason that if your having issues with the front sensor, you may get a happy meal of codes. That's not to say the front sensor is bad, its saying it's not able to respond as expected. This could be the sensor or that there's some fuel mix issue which the sensor's feedback can't correct for properly. You'd probably need to check for vaccuum leaks etc, particularly around the intake manifold, air tubing and vacuum lines which were disrupted by the repair. I would not start by assuming the cat is bad, particularly if you didn't have a check engine light before servicing the PCV system.

 

Interesting.

For the last year or so, my car spits out a spray of fluid and soot at start up almost every morning. It looks like someone sprayed one spray of a Windex bottle on the floor of my garage in the same place every morning. The car does not smoke unduly, and it does not continue to do this all the time during driving.

I assume that is normal to some degree on a 20+ year old car with over 250K miles on it. I am not really using / losing any coolant, and I'm seeing no evidence of coolant in the oil. But, this is the first time I have seen any O2 or Cat codes thrown on my car. I do not notice it running any better or worse than prior to doing the PCV job.

While I can confirm that the glove test did pass post PCV job, what are some other guages I can use to make sure the repair has the intended effects? Will I notice any increase in fuel economy? My car currently gets around 18-19 MPG doing mostly city and suburban driving. I rarely take the car on any highway driving, and when I do it is for 40-50 miles tops once a month.

 

I didn't realize that you had that kind of mileage on the vehicle. If it were me, I would have pulled the oil pan as part of the job since the oil drain into the pan can get clogged, essentially filling the breather box with oil.

If it was not full of oil or other sludge when you removed it (was it really heavy compared to the new one) then you are probably okay in that area.

I had one for resale that had the catalytic converter code and also a plugged PCV system. I did the entire system plus pulling the pan and cylinder head to clean it up. After running the car, the code has not returned.

 

thanks Tony, I did clear out the bottom port pretty well, and also put a heater hose on it and blew through it, hearing bubbles without blowing too hard. So I guess that goes to show the port was clear.

The lower port on the PCV box was about half clogged in the box and the lower portion of the box is full of crud. The new box was lighter, but not that much lighter. The lower port of the block that goes into the lower port of the plastic box was where the jam up was; there was a fairly solid plug of residue in there about 1/2" thick.

It passed the glove test after the repair, so for now I am confident that the repair was adequate at the very least.

 

Sounds like you did an excellent job.