Reading live data
Thread Starter
10th Gear
Joined: Jan 2023
Posts: 10
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From: MI
Reading live data
I'm trying to solve a PO 430 problem on my 2007 Lexus GS 350 210k miles. At 2k rpm engine hot my O2 sensors read 3.26v for the upstream and .76v bank 2 and .8 v bank 1 steady for the downstream. Lamda is .99. Short term and long term fuel trim is about .7 to 2.5. Temp on bank 2 cat is about 180 going in and 420 out hot at idle. Pressurized exhaust and did not see any leaks with soapy water. PO 430 comes on after about 200 to 300 miles after clearing. Is the upstream sensor OK reading 3.26v steady and not switching rapidly?
Intermediate
Joined: Mar 2017
Posts: 329
Likes: 182
From: SC
When was your downstream O2 sensor last replaced? If you are confident you have no leaks, and don't have a carbon build up issue on that bank, I'd suggest a new Denso O2 sensor from Rock Auto. This was the only way I could keep a P0420 (other bank) off on my 2007 GS350 with 118k miles.
Be careful, some might suggest a CAT change, but focusing on the sensors 1st is the right/cheaper approach).
I'm sorry I can't help with the live readings, but after months of troubleshooting, clearing codes, and having them reappear, my final solution was a new Denso O2 sensor.
Be careful, some might suggest a CAT change, but focusing on the sensors 1st is the right/cheaper approach).
I'm sorry I can't help with the live readings, but after months of troubleshooting, clearing codes, and having them reappear, my final solution was a new Denso O2 sensor.
Thread Starter
10th Gear
Joined: Jan 2023
Posts: 10
Likes: 0
From: MI
Appreciate your answer. Since I recently purchased the car it is unknown if the sensors have been replaced. They are probably original as the car has about 70 service records and no mention of replacement. Your experience confirms the best and least expensive route to go after making absolutely sure there is no exhaust leakage. Thank you for sharing your experience as it was very helpful.
I would double check for leaks again, because sometimes you will get a leak from the top of the joints, those are difficult to find. Did you make sure to have someone rev the engine will you examine for the leaks, also look for soot on the pipes.
If its an awd, they are prone to leaking at the mid pipes and we usually just rip off the tin covering, because that just collects water and rots the exhaust pipes.
If its an awd, they are prone to leaking at the mid pipes and we usually just rip off the tin covering, because that just collects water and rots the exhaust pipes.
Thread Starter
10th Gear
Joined: Jan 2023
Posts: 10
Likes: 0
From: MI
I was alone and without a hoist so I did not start the car but just pressurized the exhaust with a shop vac spraying soapy water on the joints. I agree, the next step is to carefully inspect the exhaust on a hoist before replacing the downstream O2
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