2007 GS350 with 115k miles, only driven 7.5k the last 2.5 years, mainly highway miles.
- Using a Craftsman CANOB2 Scan Tool, Model 20890, I've set (red light) codes P0420, P0172 and P0175. Corrected by cleaning the air filter, MAF and repairing the MAF connector housing that had separated from the wiring. Car was running rich (poor mileage), and after corrections, no DTC's and gas mileage improved.
- Even though I'm not setting any codes, I am getting 30 Readiness (yellow light) DTC's from the CAT, EVA and O2S systems. Codes are P0300, P0171, P0172, P0174, P0175, P0100, P0101, P0102, P0103, P0125, P0128, P0136, P0137, P0138, P0156, P0157, P0335, P0420, P0430, P043E, P043F, P0441, P0451, P0455, P0456, P2401, P2402, P2419, P2420, P2A00 and P2A03.
- Of course, I'd like my Readiness status to be a green light with no pending codes.
- I don't have TechStream, but do have access to the Lexus GSIS documentation for a GS300 (not the GS350).

Questions:
- Might these Readiness codes go away after driving more cycles?
- Could one or both rear O2 sensors set so many pending codes? Bank 1 seems like the most obvious culprit, but some Bank 2 codes are also pending.
- How often (mileage vs yrs) have you changed your O2 sensors or even a MAF?
- Any experience with multiple CAT, EVA and O2S pending codes and what was your corrective action?

Thank you for any input you may share.

 

I did a lengthy test drive with speeds above 45 mph and many stops with idle. I rechecked my codes and got a Pending P0420 (yellow light on scanner but no Check Engine Light on car.) I also checked the Readiness DTC's. They dropped to 20 (previously 30). Readiness DTC's were P0300, P0171, P0172, P0174, P0175, P0100, P0101, P0102, P0103, P0125, P043E, P043F, P0441, P0451, P0455, P0456, P2401, P2402, P2419, P2420 and P2610. I reset/cleared the Pending P0420 and the Readiness DTC's went back to the original 30. I've read that if you clear a pending code, your Readiness codes all reset to open for states with emissions testing (ie. for folks who clear codes right before emissions testing).
I also recleaned my MAF and air filter, double checking all connections are tight (no air leaks). Also checked for exhaust leaks on the passenger side and the connection prior to the downstream O2 sensor wasn't leaking.

At this point I either have a O2 sensor problem (Bank 1, Sensor 2), or an A/F sensor problem (Bank 1). I hate to just buy parts and throw sensors at it.

Opinions?
Anyone replace their A/F sensor?

 

Did another lengthy test today. No DTC's or Pending DTC's (ie. P0420 disappeared). Readiness DTC's still at 20 codes.

Car seems to be running well. At this point I'm not buying any new sensors and will continue to run the car and check for Readiness codes (w/o clearing non-existent DTC's).

 

These cars just need to be driven and used, when they sit for a long period of time issues like this pop up, but majority go away.

Also is this an awd? If so they do have issues with leaking mid pipes that trigger catalytic codes. So if it is awd, I would check for leaks, and remove the tin covering the midpipes. As that is the main cause of them rotting with rust.

 

Thanks for the input.

RWD car but not driven a lot in the last few years due to Covid and access to 3 other cars. No rust here in coastal South Carolina...no salt ever on the roads.

Looks like I need to drive more or sell a few of the older cars.

Never paid much attention to the Readiness DTC's, but I'm assuming they will go away when I drive more over the next few weeks.

Thanks again.