2004 to 2016 Mazda 3 Forum and Mazdaspeed 3 Forums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
Hey all, just discovered this forum and wanted some guidance on the next steps for my Mazda 3 2012 2.0L.
My car wouldn't start (battery is new), it would turn over but just wasn't catching. Brought it to the mechanic and they replaced the MAF (Mass air flow sensor) $400. This got the car running pretty smoothly again. About 2 days later, I get an engine light, bring it back to the mechanic and he says its running too lean. He was able to clear the light but it came back in. Long story short, he wants to charge me another $400 to replace the downstream oxygen sensor. I refused and took my car back. I'm going to buy the sensor and do it myself.

Has anyone encountered an "engine running too lean" engine light and was able to fix with the downstream oxygen sensor. Mechanic is saying its Bank 1 Sensor #2 - is this the one after the catalytic converter?

Thanks for your help!
 

·
Super Moderator
Joined
·
4,449 Posts
Bank 1 Sensor #2 should be the downstream sensor, after the cat. Usually its the upsteam sensor that triggers a lean condition code though. Don't throw parts at the car and don't guess at what you don't know. Go to the autoparts store and get a cheap code reader, plug it into the OBD port and get the code. Once you have the code you can maybe figure out what the problem actually is. Running lean could be a lot of things, many of which might be the direct result of this mechanic doing something wrong.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #3
I have no doubt its directly related to what the mechanic did. His theory on the downstream sensor was that it was reading improperly and causing the car to overcompensate/make adjustments (something like that) which in turn was causing the car to run lean. I'm no expert so I assumed this was correct.

But yes, I did just buy a code reader and all I can make out is "too lean" on the reader. nothing more.
 

·
Super Moderator
Joined
·
4,449 Posts
If the MIL is on there should be an associated code such as P0174. If the reader doesn't show the code take it back and get one that does.
Check for vacuum leaks, loose clamps, plugs or wires, anything thats not assembled right.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #5
Thanks. Hopefully I can find a code on that reader and will check the car up and down for anything out of the ordinary.
 
1 - 5 of 5 Posts
Top