Chris Luther

TL;DR: Took 2006 RX-8 Shinka AT to dealership for “quick fix” alignment/toe settings and REAR 02 sensor replacement after CEL triggered. They insisted on a diagnostic scan at $1XX to properly address the issue and repair the rear 02 sensor which would be applied to the cost of the sensor (altogether ~400). As this was two weeks ago that I handed over my car for a loaner, a Mazda 6 which is actually quite nice, they have since stripped the thread on the FRONT O2 sensor (I received it bent to hell with some internal threads attached) and had to take out the exhaust manifold to rethread it (even after I asked if they could tap it) while claiming the front 02 and not rear 02 was problematic. After multiple drives to clear ECU and recheck, they continue adding labor for a CEL they still have not fixed and do not know how to proceed. (>$1,000) Am I being ripped by incompetent mechanics or is a mazda vehicle too complex for their own “Master Technicians” to properly diagnose and fix? Why would they replace (and stip in the process) the front 02 sensor with a rear 02 sensor voltage trip? I must be taking crazy pills.



DEETS: My previous posts have better detail of vehicle history but this vehicle received a 2007 engine replacement a couple years back and in the last year has had the rear brakes, tires, plugs, coils, wires, engine mounts replaced as well as regular 3-4k oil changes, premium only fuel, and transmission fluid flush. I had previously (2 days prior to taking it in) checked the diagnostics using an Advanced Auto Parts OBD2 scanner which indicated a P0037 B1S2 trip indicating low voltage to the rear oxygen sensor heater circuit (photos of rest of OBD2 data to follow). As I usually prefer to work on maintenance items myself with the company of more mechanically inclined friends and their oh-so-envied tools/garage (+beers), I decided to let the dealership fix my issues as I do not have the time in this month to take care of these due to a busy work schedule with multiple out of town trips. The rear 02 sensor replacement and alignment advanced into a Mazda diagnosis using their scan tool under mode 6 showing low frequency misfires on both rotors, cat conv# around 2.82 with a faulty front 02 sensor and indicating the rear 02 is fine. The tech claims the front sensor was bad “because of the drops from uA to mA.”???? Technician diagnosis was that misfires could be low compressions or most normally when coils go bad (I replaced coils/wires/plugs 2 months ago – NGK through Mazmart). He claimed the catalyst efficiency #’s should go down after replacing the front sensor. He also mentioned the rear leading coils have a “slow strobe, but all coils are firing.” Rear sensor is turning on and off but “working.” Front sensor keeps dropping out of uA reading to mA .

His prognosis and fixes:
Start with a front airfuel ratio sensor
Clear codes
Reset mode 6
Drive 30 min to 1 hr
Recheck cat numbers & rear 02 operation

After replacing the rear 02 sensor and driving it around a bit to reset the ECU, the light is still on and now will not give a CAT reading (now 0) or CEL code; rear 02 readings are 0. As the tech cannot make a decision they recommended I just come pick it up to drive it around and hope the light goes off or leave it with them to keep driving around hoping to get a CAT reading. WTH


Link to OBD2 and removed front 02 sensor:
<iframe class="imgur-album" width="100%" height="550" frameborder="0" src="http://imgur.com/a/CNtaU/embed"></iframe>

<iframe class="imgur-album" width="100%" height="550" frameborder="0" src="http://imgur.com/a/CNtaU/embed"></iframe>

Did the front 02 really need to be replaced? Should I be more worried about the cat or the rear 02 sensor? If it is the cat, should I just gut it or replace rather than keeping it in the hands of inadequate technical support to figure out. I really love the mazda vehicles i've driven and hate to discourage anyone but issues with this vehicle seem to evade many "professional" opinions for some reason. Any advice would be appreciated.

P.S. If this needs to be moved to a more appropriate forum sub, feel free to do so. Just looking for general advice.

Loki

iTrader: (1)

Edit: never mind.

Have you or they visually inspected the cat? It sounds like multiple issues. Was there a specific symptom that prompted you to replace the coils 2 months ago?

Chris Luther

Nothing appeared to be wrong with the system but I haven't opened it myself to take a look. I replaced the plugs, coils, wires for regular maintenance and hoped to improve gas mileage a bit from initial 17-18 mpg. A month ago I got it inspected in MO (it passed), went out of town for a week, and was having no problems until a couple weeks ago. Just started up like normal from a secure parking lot and the CEL stayed on while the rest of the lamps went out. Retrieved all codes on that day. They are posted to the imgur link

m4D5c13N7157's albums - Imgur

P0037 confirmed - https://imgur.com/a/CNtaU#5

P0037 details:
https://imgur.com/a/CNtaU#28
https://imgur.com/a/CNtaU#29

B1S1
https://imgur.com/a/CNtaU#15

vs.

B1S2
https://imgur.com/a/CNtaU#16

Catalyst
https://imgur.com/a/CNtaU#19
Cat Temp
https://imgur.com/a/CNtaU#42

Misfire Cylinder 1/2 (keep in mind the engine was replaced 23k miles ago)
https://imgur.com/a/CNtaU#24
https://imgur.com/a/CNtaU#25

State OBD Check
https://imgur.com/a/CNtaU#36

Chris Luther

bump

So many views and no ideas/opinions?

Chris Luther

Update: It was just the rear 02 sensor. Dealer replaced both but only charged me for the rear 02 as the CEL did not shutoff with front replacement. CAT numbers still a little high so it may need to be replaced in the near future. Good guy Mazda Dealership. *\o/*