Bank 1 reading lean...find the problem

[Sully]

My dad's 99 toyota camry started intermittently shuttering and lunging forward kinda I guess but it only happens sometimes. But it also threw a code and I read it and it translate to bank 1 O2 reading lean. Now this could be several things according to the Internet. Including clogged fuel filter and clogged/dirty injectors. Or a dirty maf but i thought I read this car has a map(which would be pressure I guess) Or a vacuum line iirc. Of course it could also be a faulty O2.

Anyone have any advice on what to start and eliminate first. I would think anything clogged before the fuel rails split, would cause both sensors to read lean unless bank 1 just was worse at the time it triggered the light. That statement would apply to the maf too I would imagine.

A few months ago the charcoal canister vent code popped up but after resetting it stayed off and it seems it can pop up when the tank is low or something like that.


Edit: it's the 3.0 v6

[Jake]

My M3 threw similar codes and it ended up being shitty spark plugs. I got like four codes and the bank 1/bank 2 reading too lean were definitely part of the list.

[Sully]

Hmm not sure when the last time they were replaced. Certainly could be bad. This was my grandfather's car so from 1999 to 2012 it acquired roughly 36,000 miles and sat alot in the last year's when he didn't drive much. We've put another almost 30,000 on it since we got it in 2012.

The only thing is, did you also get a misfire code with those? Usually the ignition system is one of the first codes to pop up.

[Jake]

I think it said something about a misfire on one cylinder, but then both banks were too lean, and something about the cam position sensor. It *freaked* out.

[rherold9]

Clean maf or map. Check plugs. That would be the two first things I would do

[Goodspeed]

My parent's Avalon with the 3.0 V6 had this code pop up last year - it was the O2 sensor.

[ViPER1313]

My experience has always been if it's a single bank running lean, it's most likely the O2 sensor. If you want to troubleshoot it on the cheap you can usually swap the front and rear bank O2s and see if the lean code follows the swapped sensor.

[Sully]

Any idea what that would be? Would I be incorrect in assuming bank 2 would be the other side of the engine? What bank or reading would you get for the secondary O2 location? Or by front and rear, are you saying the other side of the engine but the primary O2 sensor. I feel like that makes more sense after typing it

[ViPER1313]

Other side of engine, primary O2 sensor

[D_Eclipse9916]

Code should read out if its a bad o2 sensor (can also be a dirty MAF or plugs, but is 99% of the time an 02 sensor): Bank 1, Sensor 1, or Bank 2 Sensor 1 or the likes.


Bank 1 vs bank 2 in reference to a V-type engine is one side or the other.
Sensor refers to the 1st in line or 2nd in line.

So if it reads Bank 1 Sensor 2, its the first bank side, post-cat o2 sensor.
Bank 1 Sensor 1 would indicate first bank, pre-cat o2 sensor.

[Sully]

Thanks, that makes much more sense and seems pretty logical this morning. Last night when I replied, i was..... not logical