how safe to drive car with po 135 ?

Question

The engine light came on, no other trouble, 156000 miles on car

Answer 1

P0135  A electrical problem primary heated 02 sensor

You can drive this vehicle  and there would be little or no noticeable drivability problem , what you would notice would be a decrease in the fuel , What the primary 02 sensor does is keep the engine in fuel control. The worse case is that you can hurt the ECM driver for the primary 02 sensor ,