techno
New member
Basically, the only difference between the two error codes you have had is that the P1135 is being a little more specific as to what the issue is. P0420 can be a symptom of P1135, if you follow me.
As long as your mechanic bought a new A/F sensor for the front and used one of the two new O2 sensors that you purchased for the rear then you should be fine. The O2 sensor can not physically be used in the front (the electrical connections are different) so there is no way he can mess that up.
So, provided that the old sensors were the cause of the problem in the first place (they usually are), then I'm predicting that your problems will be solved.
As long as your mechanic bought a new A/F sensor for the front and used one of the two new O2 sensors that you purchased for the rear then you should be fine. The O2 sensor can not physically be used in the front (the electrical connections are different) so there is no way he can mess that up.
So, provided that the old sensors were the cause of the problem in the first place (they usually are), then I'm predicting that your problems will be solved.