P0135 Check Engine Code

[Markuses300]

Hey everyone,

My check engine light came on my '98 ES300. Auto Zone said it was the P0135 check engine code, Bank 2. I replaced the O2 sensor behind the Cat and reset the light. Today the light came on, same code except it is Bank 1. So I ordered a new O2 sensor (Bosch) and I'll change it out when it comes in. Just wondering if there is a third that I need to replace? The kid at Auto Zone says I have 2 and I know the 2000 model has 3.

Thanks

[lenore]

There has been a lot of discussion about those o2 sensors. They are actually air/fuel sensors mounted on the exhaust manifolds, Bank 2 is the the front of the engine next to the radiator. Bank 1 sensor 1 is the exhaust manifold sensor between the engine and firewall. The O2 sensorz(Bank 1 sensor 2) is mounted just before the catalytic converter about even with the drivers seat under the car. Now the bad news, the Bosch sensors do not work well on our cars. You need to get original equipment Denso sensors. Sorry, but it has been tried before and the final fix is back to Denso original equipment sensors.

[Markuses300]

What is the best approach to fix the problem? Should I replace all 3 of the sensors with Denso sensors? Or should I replace them one at a time? The sensor under the driver's seat has been replaced with a Bosch unit. The other Bosch one I have in the mail, I guess I'll need to return it. This is a bummer, I just want the light to turn off.

[lenore]

i would only replace the Bank 1 sensor 1 which is the one between the firewall and engine. Here is the air/fuel sensor in question: