Engine Management Light

[Willis07]

Hi

Please can somebody offer some advice. I have a Toyota starlet SR 1998 model, non turbo and recently the engine management system light has been coming on. It seems to only come on when the car has reached about halfway on the temperature dial on the dash, then it comes on and goes off intermittently.

I took it to a local Toyota service garage and they did the diagnostic checks and advised that the fault codes were PO21 and PO22, the oxygen sensor and the coolant temperature sensor needs replacing. I cant afford to pay what they are asking for the work so have tried to fix it myself. I have bought the 2 sensors the local auto parts shop have suggested they are, they looked them up in the parts catalogue and i have since replaced them but the light is still coming on.

The only oxygen sensor i know of is on the exhaust before the cat converter and without a repair manual i just don't know if any others exist on the car. I have heard this model has more than one but i physically cannot locate any others. I think it may relate to Bank 1 & 2 sensors but don't know how to locate them.

Any suggestions please, or a picture from a manual that would help me locate other oxygen sensors on this model.

Thanks in advance, any help would be much appreciated as this has cost me a load of money so far and the light is still on.

Willis07