When the cheaper, non-OEM oxygen sensors failed to resolve my car's ECU 'check engine' code, I purchased the identical parts that came in the vehicle from the factory (Denso, which is the same part sold by Toyota dealers with a Toyota part number at a huge markup). This is the second time this has happened to a family member's car and Denso sensors have resolved the issue on both occasions. Unlike some cheaper generic sensors, these not only work to original specs (duh), but will last much longer than the generic (or Bosch) substitutes. So, these should last well over 100K miles like the original ones they replaced.If replacing these yourself, it's a relatively easy job. Just unplug the harness, unscrew the old sensor, screw in the new sensor, and plug the new harness back in.If care and the proper tools aren't used, however, one can easily strip the threads, since the heat seems to 'weld' these sensors on over time. I recommend PB Blaster (to avoid stripping the threads) and going slow on seized sensors. Use a six-sided O2 socket (or 6-sided wrench in the tight spaces of some newer cars), and make sure the force you exert is parallel to the threads. Avoid straining with a small socket wrench, as it tends to casue the force to 'tilt' the sensor, which can leave the softer metal of the sensor threads stuck in the exhaust's sensor port. Avoid this, even if it means using a breaker bar or pipe extension. Having to pipe-tap the threads or pay a mechanic to do it will totally ruin your day.Also beware shady mechanics, who have been known to remove good sensors and replace them with faulty ones, in order to rob you of $300 or more to fix it.Use a good OBDII scanner that has the ability to record all the ECU/sensor readings prior to leaving your car with a Mechanic. Then when the scumbag tries to scam you, report it to the authorities.