Replaced EGR valve, now get p2226, barometric pressure sensor
 

This is on my 2004 Mazda6http://images.intellitxt.com/ast/adTypes/icon1.png SportWagon with the 3.0 V6 and manual transmission. I replaced the EGR valve and gasket after getting a code for that. CEL still on, now with p2226 (barometric pressure sensor). Car runs great, from idle to around town to highway. In fact, just got back from a drive from Baltimore to Austin with no problems.

All vacuum hoses in good shape and tight, electrical connectors to the 2 sensors on the firewall not corroded and seated properly. Getting full vacuum signal from the EGR valve to the barometric sensor on the firewall (17-20 in Hg) but replaced the vacuum line while I had it off. Also sprayed the electrical contacts on the connector.

Any other ideas of things to check? Are these barometric pressure sensors known to fail?

Thanks for any insight.

Doug

Anyone know if these barometric pressure sensors known to fail?

That would be a rare occasion. You already made sure the vacuum lines are good and open.
Unfortunately I cannot pinpoint this one. The next thing I would check is the electrical stuff. I would want to know if there is an electrical signal arriving at the pcm. I don't know enough to give you details on that.

As I just posted in a thread from 2009 titled "CEL P1487 P2227", my P2226 barometric pressure code is now gone but I now have these two. Also have P0431 and P0421, indicating pre-cats are used up. I did run some wire through the ports on the 2 sensors on the firewall and the one with the Mitsubishi logo and K47 markings did seem a little plugged up. Was also seeing 5V on one pin and ~2.5V on other pin with key on and engine off.

Any further thoughts? It appears the pre-cats are a normal consumption item, and with 131K on the car not surprising.

My thoughts: New O2 sensors with that hi mileage.
Run lacquer thinner ( not paint thinner) thru to clean catalytics, possibly may clean O2's if you don't want to buy new ones.
READ: Reasons for catalytic converter failure. | eBay

Watch these video:

I'd never heard of putting lacquer thinner in the tank. After that video finished another appeared from EricTheCarGuy where he took a mythbusters approach. He found it not to work on his Subaru, though he only put a quart in when Scotty said to use a gallon.

Anyone ever try this on a Mazda? What were your results?

I've done it @ 1/2 strength. I didn't have a pre-cat but put it in to help clean things. Ran great afterwards.

I believe Tanprotege also did this. If you're going to test it, test it properly, 1 quart is nothing! Eric the Car Guy did a half-assed effort on that one!

I like EricTheCarGuy, but this attempt at myth-busting is no good. If you want to test a procedure you cannot nilly willy change it.

That said: this procedure only works if there is dirt on the catalytic converter that can be dissolved by the Lacquer Thinner. If the catalytic converter is clean already or it is contaminated with something that does not dissolve (silicone?) it will have no effect.

Ask yourself: what can you loose by doing this? What if it works and you did not try?

I have done it with 3 vehicles and all of them had better throttle response after. Since the solvent will go through the whole fuel system and the exhaust system everything gets cleaned, even the O2 sensors.

It also does not work if your catalytic is melted!