So I got my ECU tuned from JET chips, Put it in, everything works fine for about 120 Miles, CEL came on, I didn't get them checked so I reset the battery cable just to see if the CEL came on because of some random voltage spike (it's happened quite a bit before). Anyway, after I reset the ECU, less than 4 miles, or immediately I turn on the car, what do you know, the good ole CEL comes right back on. I throw 6 codes, 3 legit, 3 "pending" which are the exact same codes.

p0032 - Pre-Cat sensor heater circuit too high
p0038 - After-Cat sensor heater circuit too high
p0034 -Which really boggles me. Everything I could find for this code says, "P0034 Turbo Charger Bypass Valve Control Circuit Low." Ummm. that's cool except I have a 04 3i 2.0L Auto, as much as I want a speed3 there is no turbo here.

There are 150,000mi on the car. Car runs great, still getting decent gas mileage. I'm guessing these codes are related to the tune since they state that they change the a/f mixture from 1000rpm's to WOT. I was wondering if running if running premium fuel would turn off the CEL? Purchasing cooler O2 sensors? Bad ECU tune? Right now I'm running mid-grade ~89 octane. Or is it really sheer coincidence that BOTH O2 sensors went bad at the same time...

 

Hmmm, NO TURBO! LOL. Who said computers were smart.
What does the JET Chips recommend for Fuel Octane. I would go 91. You may have to wait until this tank is dry, put 91 in and reset ECU. I don't think JET took into account your other mods. I see you have a timing mod?
The second thing I would do (later with 91), is put it on the DYNO and get your air fuel ratios (afr). Optimal afr in power band is between 12.5:1 and 13:1 for Non Turbo Cars (of which yours is?!). Above 13:1 is too lean for afr, below 12:1 is a bit rich. Normal driving (barely stepping on gas pedal) is around 14.7:1 afr.
If your car is on the rich side, installing a throttle body spacer will lean out afr by around .5 IE: before spacer your afr is 12:1, after installing spacer your afr is 12.5:1.

 

That's the thing. JET took into account for the mods that I have done on the car. I specifically told them them that I had a Cold air intake. 2.5in cat back exhaust. Power pulley kit including (water, alt, and crank). I didn't tell them about the timing mod. The "timing mod" is sliding the crankshaft position sensor up and down to trick it into "advancing" the timing so slightly that it almost makes no difference...

 

Timing is one of the things re-programming does. I would go definitely go 91 octane and maybe revert your timing mod after that. The Octane rating of a fuel restricts how far advanced timing can be. (Low octane rating requires a more retarded ignition timing and a high Octane rating allows a more advanced timing to be used: Tech Dept
If you have advanced the timing beyond stock spec, you may not be @ ideal position. You actually may require 94 octane.

 

Yeah, I will side the crank position sensor back to where it was and go to premium fuel but will that really solve the CEL's, The heater circuit being to high? I have no codes saying to its too rich or lean.

 

Since you just had problems after installing it, try it. I wouldn't do anything else until you try this experiment. Wiring on install?
Otherwise you could try removing the chip and see what happens.

 

There is no "chip" for our car, They actually reprogram it completely. Plus they have a warranty on it, it you break the seal around the ECU it voids it.

 

Reprogramming ECU is the best way, better than piggy back wired in. You must have had your car sitting for a while.
I can't really see both O2 sensors going at the same time. I found the following good read about Mazda 3 with P0032: mazda 3 p0032 and p0038 codes : OBD-Codes.com : "Today I decided to check the fuses for my O2 sensors. Now I feel massively stupid for never doing this in the first place!!! Both are missing! My guess is the the exhaust shop got rid of them thinking that it would make my O2 light go away. I have no idea why anyone else would do this".
Your lucky I woke up early this morning and not taking a shower (had 1 yesterday & freeing up time to find this for you---LOL). I have an appointment @ 10:00 am!
And NO, I don't know where those fuses are.

 

The car never sat, once. I actually had gone to my local junkyard and bought and ECU from a totaled Mazda3. Made sure the serial numbers matched and all that. We were kosher on the ECU being a still usable ECU. So while still having my own original ECU in the car drivable and all that I went to the dealer had them scan in the VIN number into the PCM/ECU. Once they did that, I shipped it to jetchips. They gave me a box with questionarre asking me all the mods I have done to the car. I filled it out shipped it to them, they tuned it sent it back to me all while I was still using my original ECU and car as a DD to work. Two days later Mazda scan in my keys into the newly tuned ECU, plugged it in and everything was fine. Like I said, drove it for about 125 miles, everything was fine then these three codes showed up. I reset my battery for grins and now it pops up after about 4 miles. I don't think the 02 Sensors are bad. I never had a problem with them with the stock ECU. I think either JET ruined the ECU while tuning it OR the tune itself is bad. However, I'll check the fuses for grins, I guess it can't hurt. I'll be calling them tomorrow to figure out what is needed to fix this....I.e.running premium fuel etc.

I will say, the tune made a world of difference. I'm still achieving decent gas mileage for 150,000miles 04 2.0 auto. I get a combined 30 city/hwy. There is a solid pull through all the gears. No gear seams slumpy compared to the other. Shifting in manual mode seems to lock in and is precise. Throttle response is instantaneous, no lag what so ever. If there is anything that I'm more impressed with than anything is 2nd gear on the auto. 2nd gear is so damn tall and its slower than fresh wet dog **** sliding down hill. With the tune, it pulls strongly all the way to red line. Even the overdrive on the highway just pulls better, quicker acceleration. I find the car is not reaching for the overdrive as often either, going uphills on a highway.