Q: low idle around 400 rpms

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it has this low idle however it does not fluctuate and does not stall. it stays right in place. maybe this is a lack of back pressure? the car is straight piped with true dual pipes and the stock y pipe. can this be a hint to any other major problems?

My car has 193000 miles.
My car has an automatic transmission.

This generation of Lexus GS models has a known issue for this and can often be corrected by cleaning the throttle body. I would also recommend testing the MAF (Mass Air Flow sensor) as well as this can lead to a lower than normal idle depending on the message it is sending to your car’s ECM (Electronic Control Module).

I would also test/check the O2 Sensor (Oxygen Sensor), which is a sensor that monitors the air/fuel content coming from the exhaust.

Based upon these readings, the messages are relayed to your car’s fuel injection system which then tell it what corrections to make.

If you need some help with this, feel free to contact a certified technician, such as one from YourMechanic. They will be able to help perform these checks to diagnose your low idle and help you fix it accordingly.

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