Help With Some codes 98 Avalon

[SomeoneHelp]

OK well this is my first post so here it goes.
I have been getting error codes: p0125,p1133,p1135 and p0171. The last one is werid but it only can on the last time I check. I believe p0125 is because of the other 2 p1133 and p1135. The last p0171 is about the mass air flow sensor. The thing is where is the o2 sensor that I need to test ? or just replace? This problem has been happening for sometime. I will do another check today but I believe it is the same. The other thing is that we have replaced the o2 sensor that is under the passager seat.

Code: p0125 , p1133, p1135 and p0171

where is the location of the o2 sensor and where is the one that needs to be check. Also we have CA emission (I believe that is what its called)

Anyways thanks for the help. This have been given us trouble a couple weeks. Any help would be nice.

Anything else needed just post

[nhparrot]

P0125 Insufficient Coolant Temp. for Closed Loop Fuel Control (Except California Spec.)
 Fuel system
 Injection
 Ignition system
 Gas leakage on exhaust system
 Open or short in heated oxygen sensor circuit
(bank 1, 2 sensor 1)
 Heated oxygen sensor (bank 1, 2 sensor 1)
 ECM

P0125 Insufficient Coolant Temp. for Closed Loop Fuel Control (Only for California Spec.)
 Open or short in A/F sensor circuit (bank 1, 2 sensor 1)
 A/F sensor (bank 1, 2 sensor 1)
 ECM

P1133 A/F Sensor Circuit Response Malfunction (Bank 1 Sensor 1)
 A/F sensor (bank 1, 2 sensor 2)

P1135 A/F Sensor Heater Circuit Malfunction (Bank1 Sensor 1)
 Open or short in A/F sensor (bank 1, 2 sensor 1)
 A/F sensor (bank 1, 2 sensor 1) heater
 ECM

P0171 System too Lean (Fuel Trim) (Except California Spec.)
 Gas leakage on exhaust system
 Air intake (hose loose)
 Fuel line pressure
 Injector blockage
 Heated oxygen sensor (bank 1, 2 sensor 1) malfunction
 Mass air flow meter
 Engine coolant temp. sensor

P0171 System too lean (Fuel Trim) (Only for California Spec.)
 Air intake (hose loose)
 Fuel line pressure
 Injector blockage
 Mass air flow meter
 Engine coolant temp. sensor
 A/F sensor (bank 1, 2 sensor 1)

[SomeoneHelp]

Wow thanks that helps alot. Couple more question is where are the sensors like (bank 1, 2 sensor 1) ? That is a little confusing. The other thing is there any plan I should follow to fix it? I have been trying but doesn't seem to work. Should I just replace the 2 sensors in front because it seems like that is what is causing the problems ?

nhparrot for the information.

[larsdennert]

I'd try cleaning the MAF sensor. It probably has dirt on it preventing it from working properly. A common problem when driving in dusty environments. I've had that a few times.

The MAF is located in the air intake stream and uses a heated wire to measure the Mass flow. The faster the wire cools, the more mass (speaking simply). When it has dirt, on the wire, it no worky. Carb or electrical cleaner works. The oriface is only about 3/8" big in the sensor.