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2005 Lexus 330 Engine Issue

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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 a much lower price quoted by the original repair shop. Unfortunately, that repair shop (and other local shops we've called) will only install parts which they order in house due to strict procedures. Therefore, because we 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!

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  • 2 weeks later...

Hi- Ok, brief update- we changed both air flow sensors, then reset the code, and now the check engine and track off lights have both turned off. However, the VSC light is still on. Does anyone know if this is still some code that needs to be deleted or reset? The car still seems like its running fine. Thank you!

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Thank you for the reply. We re-scanned the car and it came up with the same P0031 code it did with the old, defective oxygen sensors. The auto shop owner said the code could be a "holdover" since it wasn't completely cleared due to the continuing VSC error, but he said since the check engine light was off, it's unlikely to be an actual engine issue. He also said the VSC sometimes locks after a major abs breaking event, or it's possible the sensor could have been tripped or locked during the oxygen sensor replacement. Any ideas where we should go from here? Thanks again for your help.

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