StanVanDam

My check engine light turned on while driving normally on the highway on Saturday. No other malfunction indicators or messages were active, and the check engine light remained on even though I turned the car off and on during a few errands around town.

On Sunday, I borrowed an OBD-II code reader from PartSource to pull the code DTC P0155 OXYGEN SENSOR HEATER CIRCUIT MALFUNCTION (BANK 2 SENSOR 1). How do I know if the heater circuit has malfunctioned or if the O2 sensor needs replacing?

When I started the car after disconnecting the code reader, my VSC OFF light came on, with the message Check VSC. My Sport light was also blinking. Did the code reader do something to the car?

I went for a drive and after a few kilometres, the Check VSC message changed to VSC 39, which I think is a problem with the left rear speed sensor. Does anyone have any tips for troubleshooting this sensor?

After I finished that drive and turned the car off and on again, the Sport light didn't blink anymore and the VSC 39 message never showed up again after several drives across town, although the VSC OFF light was active and the Check VSC message was still there.

What would cause the Sport light to be blinking and then stop blinking? Why would VSC 39 show up only once instead of all the time? No maintenance had been performed recently. Gas cap is tight, and engine air filter hasn't been touched since last summer.

Could this problem be caused by a weak battery? My 3 year old battery has been drained by accident 4 or 5 times to a level too weak to start the car, after which I've always used a battery charger with a 75A start mode.

Can these lights be reset by unplugging the battery for awhile, or do I need a Lexus scantool? Another forum user with VSC 39 took his car to the dealer and they just reset the lights because they couldn't find a problem - https://www.clublexus.com/forums/2362277-post26.html

Thanks for any insight!

StanVanDam

I've cleared the VSC code using the OBD2 port jump with a paperclip and reset the light by pulling the battery for half the day (cleaned corrosion on the terminals with baking soda paste and applied dielectric grease). The CEL came back after ~15 minutes of driving. Did not pull the code yet but I suspect it is still P0155.

I think connecting that non-Lexus code reader triggered the VSC light to go on and caused the Sport light to blink..