Hi, My daughters 98 Cavalier 2.2L has given us 3 codes:

125 = insufficient coolant temp.for closed loop
this sounds like it needs a new coolant sensor and have no idea were its located ?

134 = O2 no activity

1133 = Insufficient switching rear O2 sensor
Last year we replaced the thermostat and front O2 sensor
now it seems we need a coolant sensor and rear O2 sensor

Does any one know if this is a correct assumption ? and just were is this coolant sensor?

Thanks,
Dad

 

sounds like a thermostat will fix all problems
how hot is the heat coming out of the vents?

 

He's already replaced that.