The P0420 code is setting because the PCM is asking the car to go into "closed loop" prior to the time it takes for the O2 sensor to warm up..

This problem is addressed in the 29.2 reflash.

Mark

 

P0420 can be set on a warmed-up car. I'm proof of that (got it 5 times, always after having driven at least 15 miles). I got the reflash, and have maybe a .5MPG improvement, if anything at all. The power feels different, though. No more big kick at the higher RPM when the ports open. It still feels pretty quick, but I like better the way it felt before the reflash. On the positive side, 2.5 tankfuls since reflash and no CEL.

 

The "L" version is the latest and greatest. We have surmized it's done by Japan, and is now a world wide build. It fixes some sensor problems, and re-maps the fuel. Maurice is getting -better- mileage. He's worried about how lean it is now, so will be recommending all owners of Stage 1 get it updated. He also recommends everyone who can get the re-flash done. For more, watch for his post this weekend in the "Canzoomer" vendors forum.

BTW, the knock detection system on this car is very good. Unlike previous RXs, it will not allow the engine to destroy itself. You would really have to try hard to damage an apex seal.

 

Does the L reflash apply to euro spec cars?, as I spoke to my UK dealer today and they didn't know anything about it!

 

A couple weeks ago, I got a P0420 too. Power Mazda reflashed the ecu. I've noticed that the car does'nt load up the spark plugs as much. Before the ecu reflash, I'd have to spin it to 9k+ through a couple gears to get a smooth idle. After the ecu reflash, I can drive alot more low RPM miles before it needs to be cleaned out. CJ

 

Just because the car was warm when the light came on doesn't mean it set at that time..do you have the freeze frame data?

The car will store some codes until a "OBD-II drive cycle" has been completed.

 

Found the sticker on my hood that the Mazda tech used, here is what it says:

Reprogram PCM -- N3H6-18881-L -- 2/24/04

So I did get the "L" reflash.

Prior to the reflash, I have averaged 21.12 mpg, based upon 35 tankfuls. The (1) tankful since the reflash I got 22.67 mpg.

I do notice more hesitation below 3,000 rpm's, but I believe I can learn to compensate with new throttle / clutch applications.

My last (5) tankfuls have been 87 octane, instead of 91+. That change netted me 0.5 mpg increase, with very little performance loss.

Individual results may vary

Happy reflashing !

 

Kudos to Mazda for trying to help with the MPG issue. They are dedicated and true to the voices of the consumers!

 

Yeah, but the real treat would be if they'd inform their dealerships about the reflash procedure so they'd know what people are talking about when requesting a reflash - and also, if they would do the reflash when people complain about the low mileage, without trying to justify it even more.
According to posts on the board, this is not the case... dealerships either don't know about the reflash or give owners a hard time, asking for some other reason like a CEL.
If this was an attempt from Mazda to improve the fuel mileage, then all owners should get a notification about it... of course that would not be a good thing from the marketing point of view.

 

Tamas, which dealerships in the Bay Area have given you a hard time? Just curious to see if the one I plan to go to is one your list.

 

None yet since I didn't try to get a reflash. As I wrote, this is according to some posts on the board from people who said that they were asked for other reasons than fuel mileage and that according to the dealer's "tests", the numbers are normal (whatever that means).
What I'm trying to say is that if this was indeed Mazda's attempt to improve the fuel economy, then there should be no hurdles for owners to get a reflash. Thus, I'm not sure if this 'L' reflash is indeed targeted to fix the mileage issue... but what do I know :D
If someone in the Bay Area knows of a dealership that DOES do the reflash without problems, please post.

 

P/N for current reflash is N3H6 18 881L

 

Tamas...

You are absolutely correct. The dealers (if my local service manager is straight) are ignorant of all the changes really in the "L" reflash. He called Mazda right in front of me and a Mazda Tech told him the "L" flash was to fix a couple of code problems. That it has NOTHING to do with improving mpg.

 

Face it - Mazda will NEVER admit that there is a mileage.

The have not even made any claims as to the mileage that the RX-8 will acheive.
The Federal Government did that.

I am as pissed as anyone that I only get 13 MPG at all times in my RX-8.
However, the possibility that a PCM re-flash will fix that is slim (having seen how the fuel curves are most of the time, anyway) and even if it were fixed in a re-flash, it would only be a side effect and not the stated purpose of the new code from Mazda.

 

It does make sense from a marketing and legal standpoint. Any "official" talk of a mileage problem/issue would be off-limits. Carmakers always make ongoing adjustments and improvements in any number of areas, so they can provide "updates" under that general context without explicitly labeling it. They might put out a revised or updated PCM reflash without officially stating that the primary objective was to improve mileage (or to increase HP at moderate rpm). Fixing small bugs here and there to make the car run smoother and generally better (whatever that means) might be truthful and accurate in a general sense even if some specific outcomes are improved mileage and HP at moderate rpm.

I just can't see them, under a hailstorm of HP and mileage concerns from day one, talk directly on those topics or give existing owners a heads-up.

 

I've called, e-mailed and sent a letter to Mazda NA about my gas mileage. I average about 13-13.5 with mixed driving. That is horrible.

Anyway, here's the e-mail response I got from Mazda:

--------------------------------------------------------------------

"Thank you for contacting Mazda North American Operations. I appreciate the opportunity to respond to you.

Please understand, the gas mileage estimates reported on the window label of your vehicle are for comparison purposes only and will vary depending on options, driving conditions, driving habits and the vehicle?s condition. These estimates are based on a mathematical formula provided by the EPA and are not the result of actual road tests. There is no guarantee, either by the EPA or the manufacturer, with regard to gas mileage. You should also be aware that fuel blends impact gas mileage, so fuel economy will vary depending on climate and temperature. For instance, in cold weather climates, oxygenated fuel (which requires chemical additives) is used which greatly reduces fuel
economy.

Unfortunately, we do not have any procedures to improve the gas mileage at this time.

I will forward your comments to our Product Planning Department in an effort to provide only the highest quality products to our customers."

--------------------------------------------------------------------



Bascially, this was a "canned" response so I'm hoping my letter will get a better response from Mazda.

Ironic part is when I spoke to Mazda on Friday (3/5/04), the customer service rep said I wasn't the first call he received about the gas mileage. However, he did not know about any "reflashes" to improve gas mileage.

 

I just got my car back lasstnight after taking it to the dealership to have the recalls done.

I told them that I get bad gas mileage, about 14/15mpg and that my CEL light came on..

Well, they checked my computer and found code P0131. Apparently this is a loose connection to the O2 sensor. They fixed it and reflashed my car.. hopefully this will give me better MPG..

What affect would having a malfunctioning O2 sensor have on my mpg, if any?

 

it could cause too much fuel to be burned instead of the correct leaner mixer due to the sensor misreading the exhaust gases.

at least thats my novice understanding of it

 

Unfortunately no CEL for me. I've got my K&N intake sitting in my trunk waiting to be installed. Until I get some "response" from Mazda, I'm not doing anything. I don't want the intake to be deemed "the problem" by Mazda - because I know it is not.

 

I didnt actually have a CEL.. they just happened to find a code.. My mpg did drop from 17 to 15 in the city tho

 

Mileage dropped AFTER the reflash?

 

No, it mysteriously dropped about a month ago. I took it in for the recalls yeasterday and they found a fault code despite the fact that the CEL did not come on.. but I told them it did to try to get the update.. and they gave it to me along with fixing me O2 sensor

 

I just got my car back from the dealer who installed the 2 recalls. My service rep (who has always been very nice to work with) assured me that he tried but was unsuccessful in finding the "L" part eventhough I provided the part number. He also assured me that he will keep trying.

I really wonder why the spread of info from Mazda Corp to its dealer is always so inefficient?

End ranting.

 

there is NO PART Number for this. It is a reflash of the ECU.
Nothing more than a software upgrade.

 

Should check your information before you post.

The Mazda part number for the most current PCM calibration (flash) is N3H6 18 881L for the manual transmission and N3H4 18 881L for the automatic.