Hello,

About two weeks ago, my 2005 ES 330's check engine light, VSC, and Trac Off lights lit up on the dash. The last time this happened was about five years ago when the gas cap needed replacement- but after replacing this gas cap, the lights did not turn off right away. After driving a while, they did turn off, then turned back on, then turned off again, but then turned on and have been on ever since.

We took the car to the auto parts store for a scan, which revealed a C1201 Engine Control System Malfunction error and a P0031 Heated Oxygen Sensor Heater Control Circuit Low Bank Sensor 1 error. Finally, we took the car in for a full engine diagnostic which apparently determined the Air/Fuel Ratio Oxygen Sensor (Part No. 234-9042) was defective.

The cost to fix that sensor with parts and labor was simply too high to warrant consideration given the age and mileage of the car. Therefore, we have not fixed the issue, and while the lights remain on, the car appears to be running fine, except for diminished fuel economy.

Notwithstanding, we located replacement sensor parts with the same model number online at the local auto parts stores for approximately 1/3 the price quoted by the repair shop. Unfortunately, that repair shops (and other local shops) will only install parts which they order in house due to strict procedures. Therefore, because I don't have the skills to replace the sensor myself, buying the part separately may not be a good option at this time.

My questions are (1) whether anyone here has experienced similar issues and can offer any advice, and (2) whether purchasing the part separately (and attempting to privately hire a mechanic to install it) could be a viable option.

Thank you very much in advance for any assistance!