Check Engine Light

[deano20010]

2 of my oxygen sensors were broke so I replaced them.

After replacing them I plugged in my reader and cleared the codes, and it seems to have fixed it, when I switch the car off and leave it overnight to cool down I then start the car and the check engine light comes back on again.
Check codes and its the 2 oxygen sensors that I replaced, but after about 2 hours of driving the check engine light goes out I put in the reader and doesn't read no codes.

but it starts all over again with check engine light on with the 2 codes every time engine cools down.

[gjnorthall]

What codes are coming up - is it Lambda sensor heater failure? Were the sensors a good make such as Denso? Some cheap sensors or universal types where you reuse the old connectors can give code problems. It's just that the heater coil resistance is outside the spec range - resistance changes with temperature so may be ok hot but not cold or vice versa. Otherwise if they're a decent brand - disconnect the Battery for a couple of hours to restore factory settings 

[deano20010]

they were cheap and had already have connectors on them

[gjnorthall]

I would always recommend buying genuine Toyota (Denso), aftermarket Denso, NTK, Bosch or Blueprint (reboxed Denso) Lambda sensors. As well as heater issues - low cost or unbranded sensors are often short lived in terms of response.