# Mazda 6 - Emissions problem - ODB readings **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** mazda6, mazda\ **Created:** [June 11, 2021, 2:45pm UTC](https://community.cartalk.com/t/mazda-6-emissions-problem-odb-readings/177389 "2021-06-11T14:45:51Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![stuff\_3000\_175711](https://avatars.discourse-cdn.com/v4/letter/s/f19dbf/32.png) [@stuff\_3000\_175711](https://community.cartalk.com/u/stuff_3000_175711)\ **Post date:** [June 11, 2021, 2:45pm UTC](https://community.cartalk.com/t/mazda-6-emissions-problem-odb-readings/177389/1 "2021-06-11T14:45:51Z")
Hi all. Have a 2008 mazda 6 that failed on emissions. Readings were miles off Low Idle (700 rpm) CO 5.96 Vol% HC 271 ppm High Idle (3000 rpm) Lambda 0.81 CO 7.17 vol% HC 350 ppm Mechanic says it COULD just need a new oxygen sensor but for the age of the car and needing new brake pads he was leaning towards me scrapping the car but I love the car and hate to see waste. So wondering if anyone on here would be able to look at these odb readings and tell me if they think oxygen sensor should do the trick and then a bit of cataclean after might get me past the nct. First MAF with two revs seems normal [https://imgur.com/BK7PCMi](https://imgur.com/BK7PCMi) Worried about the cat fail on that but not sure could that be sensor 2? [https://imgur.com/KmAlkAu](https://imgur.com/KmAlkAu) (have to seperate posts out cause only 2 links for new users) ---
**Author:** ![stuff\_3000\_175711](https://avatars.discourse-cdn.com/v4/letter/s/f19dbf/32.png) [@stuff\_3000\_175711](https://community.cartalk.com/u/stuff_3000_175711)\ **Post date:** [June 11, 2021, 2:46pm UTC](https://community.cartalk.com/t/mazda-6-emissions-problem-odb-readings/177389/2 "2021-06-11T14:46:29Z")
This is with a warmed up engine and multiple 3000 revs and nothing changes. I think its meant to be close to zero mA on sensor 1? and moving back to zero but this just stays at 6.35mA [![](https://imgur.com/AHTA9Rq)](https://imgur.com/AHTA9Rq) Here is a list of all the readings at idle [https://imgur.com/hF6Mn6t](https://imgur.com/hF6Mn6t) ---
**Author:** ![stuff\_3000\_175711](https://avatars.discourse-cdn.com/v4/letter/s/f19dbf/32.png) [@stuff\_3000\_175711](https://community.cartalk.com/u/stuff_3000_175711)\ **Post date:** [June 11, 2021, 2:48pm UTC](https://community.cartalk.com/t/mazda-6-emissions-problem-odb-readings/177389/3 "2021-06-11T14:48:07Z")
Not allowing me to post the last link so had to separate it out Then a list of all readings at 2000 RPM https:// imgur. com/ ZLfqArO If you need any more readings or info just ask and I’ll post them Thank you in advance to anyone willing to give their time to reply. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [June 11, 2021, 7:51pm UTC](https://community.cartalk.com/t/mazda-6-emissions-problem-odb-readings/177389/4 "2021-06-11T19:51:17Z")
OK… What engine do you have? How many miles on it? What error codes is it throwing? Because it must be throwing several. How much oil is the engine using per mile or kilometer… I’m guessing quite a bit… maybe a liter per 2000 km or more. Your catalytic converter is likely dead (and I’d guess a P0420 error code based on O2 sensor 2), this thing is running rich, not fully combusting the mixture and burning oil which likely killed the cat… Has a compression check been done? What was the result? If it hasn’t been done, do one, report back. Lamba comes from sensor 1 and it is accurately showing a rich condition based on CO and HC.