07 Mazda 3 Dreaded U- 121 and U155 codes after changing cabin air filter

[sid4spd]

Hello guys,

My 1st post here!!!

Just wanna know how am I getting a CAN BUS U 121 and U155 codes after chaging my cabin air filter. for those of you who have changed this cabin filter, know how ^#$#%$ of a job this is. I made sure all connectors go in proper place. After, I got these codes, I drove the car around the block but found nothing... However, I am afraid of this thing stalling on me on the freeway. U121 is CAN communication lost to ABS module and U 155 is CAN communication lost to instrumentation cluster. The cluster works fine as I see the needles moving ... ABS.. I don't have the correct road conditions ( and balls ) to test it out..

Any advise is appreciated

[jeff7670]

Did you disconnect the battery before you took everything apart?

[sid4spd]

Did you disconnect the battery before you took everything apart?

Nope... and there in lies the problem may be... I suppose, while removing the connectors, I may have shorted some thing causing the loss in CAN commmnunication, prompting the ECU to flash the check engine light... I put all the connectors back and erased the codes... Then drove the car for 50 miles... nothing yet... Let's hope it stays this way...

What a B! ch of a job to change this filter man!

[jeff7670]

Ya lets hope for sure. I think Mazda first designed the cabin filter and then the entire car around it.

[RedRaptor]

In my almost 15 years of ownership, I have never attempted to change the cabin air filter myself. This is exactly why.

Bring the car into Jimmy @ StreetPerformance. Let's see if he help you resolve by putting all the connections in place.

I change my filter every 24 months and Jimmy has never failed to do it properly.

Good luck!

[Ogata]

In my almost 15 years of ownership, I have never attempted to change the cabin air filter myself. This is exactly why.

Bring the car into Jimmy @ StreetPerformance. Let's see if he help you resolve by putting all the connections in place.

I change my filter every 24 months and Jimmy has never failed to do it properly.

Good luck!

+1 He does mine with no hassle and does it like a breeze..just pay the good man his labor

[G ~ MINI]

2012 Mazda 3 GX
Not sure if its wired different.
I've changed the cabin 5 times in 7 years
and never disconnected the battery and
never had an issue.

[Ogata]

2012 Mazda 3 GX
Not sure if its wired different.
I've changed the cabin 5 times in 7 years
and never disconnected the battery and
never had an issue.

2nd gen is easier..i too have done it on my wife's 2012 with no issues.. its the 1st gen (like mine) where the fuse box is in the way.

[G ~ MINI]

Thanks !! ...This grasshopper has learned something new

[jeff7670]

Its really not that hard, just don't forget to unhook the battery.