dave3000z

Hi
Can anyone help me diagnose a problem with my 2002 rx300. Initially I was getting error code PO 171 and 174 accompanied by a misfire and high fuel consumption. Changed the plugs and no2 cyl plug was damaged. cleared codes driven 80miles or so switched off and restarted after an hour, had only driven a few miles then got vsc and engine light on again, read codes and got PO171, 174 and P1133. Would appreciate any advice.
Regards
Dave3000z

CharBaby

It still seems to be related to the A/F sensor on eithes Bank
All of your code #'s are related

P0171...System too lean-Bank 1

P0174...System too lean-Bank 2

P1133...A/F Sensor Circuit Response Malfunction Bank 1/Sensor 1

P1153...A/F Sensor Circuit Responce Malfunction Bank 2/Sensor 1(if you should get this code #)

These all pertain to the A/F(air/fuel) Ratio Sensors. Not untypical for these RX's as I seem to get these CEL/VSC alot myself

dave3000z

Thanks Charbaby
Do you know how I can test the A/F sensors, dont mind spending the cash to replace them but really dont want to go down the trial and error route unless there is no other option. The vehicle has done 117000 miles and I think the sensors are original.
Thanks again

CharBaby

I have only seen an O2/AF sensor tested on You Tube Video where a guy tested the sensors with his torch while measuring tempurature and...I think OHMS!

Baetke

Keep in mind that AF sensors are different from O2 sensors. O2 sensors (the one downstream from the CAT) output a voltage that can be measured if you know what you are doing and have the right equipment. AF sensors (the ones in the exhaust manifolds) have a current output that can only be measured by the ECU and then reported to a scan tool. If you have a scan tool, it should be able to determine if the AF sensors are working, otherwise you will probably just have to change them.

dave3000z

Thanks for that, it looks like i will have to change them and see how things go. will keep you posted.