Reporting the following codes OBDII : 99 4runner

P0171 - System too Lean Bank 1
P1131 - A/F Sensor circuit response Bank Sensor 1

Are these codes pointing to a faulty Mass air flow sensor?

Any help or experience with these is appreciated

Thanks
FiLter

 

Most likely it is your MAF which needs cleaning (usually throws P0171, but can throw others at the same time). In rare cases it may be something else (or could be a MAF which is faulty and can't be fixed by cleaning).

 

Thanks
How do you clean it?

 

That first code is most likely the maf, I tried cleaning mine, but eventually had to replace it-I got one from a junkyard.

 

I took my airbox out and sprayed the MAF liberally with electrical contact cleaner.
I saw that there was still some stuff on it and ever so gently brushed against it with a q-tip.

I wouldn't suggest you do the q-tip though...

 

I tried cleaning the AFM and that seemed to be OK until I eventually seen the light again so I replaced the AMF with a new one.

Now the light is on again with a new code:

P1133 - A/F Sensor Circuit Response (Bank 1 Sensor 1) (Toyota)


Any help or expirience is appritiated

Thanks

 

filter,

google "OBDII codes"

bob

 

what do you mean?
I use google for plenty of research.