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GS - 2nd Gen (1998-2005) Discussion about the second generation GS300, GS400 and GS430 (1998 - 2005)

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Old Feb 11, 2019 | 12:05 PM
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Replaced spark plugs. Now car is throwing code. Reset light by disconnecting negative. Ran great for eight miles. I had reset trip a. Popped light while driving. Loss all pedal unless floored. Barely moved. Opened hood pulled negative. Car started and I made it home. All I did was change the plugs. Unplugged things etc. is there some reset I need to do to get the throttle to act properly?
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Old Feb 11, 2019 | 12:42 PM
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Step 1: what's the code?
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Old Feb 11, 2019 | 01:44 PM
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I did not make it to the auto parts to check for a code. There was no acceleration at all. Floored it would barely move. After I disconnected the negative it ran but I just pulled it into the parking lot and left it. It will start now but no light and it idles fine. I’m afraid to put miles on it and get stranded. Is there some sort of relearn after my disconnect of TPS when I did the plugs?
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Old Feb 11, 2019 | 06:40 PM
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There is not.
Again, step 1 would be to check the code. It will tell you what sensor is not providing a normal reading.
Until it reappears, double check that you plugged everything back where it's supposed to, and securely.
I've attached a diagram you can use as a checklist.


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Old Feb 11, 2019 | 06:47 PM
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Default Thank you

ok. So far no code has popped. Sort of hesitated at a light so I pulled over and adjusted the cable slightly. Now it is not hesitating. No light yet. Trip a days almost ten miles now. Popped last at 8 miles after clearing. We shall see I will let you know. Thank you for the diagram. I will double check everything in the morning. Also been using low octane gas. Now using only premium. That can explain a lot too.
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Old Feb 12, 2019 | 05:24 PM
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I just have a few questions about the gs300. I’m looking to get an 04 gs300 with 100k miles. I was wondering if there is anything I should check for before buying and if there’s any major repairs I should be on the look out for if I purchase the car. Thanks for the help In advanced.
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Old Feb 12, 2019 | 10:40 PM
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Default Gs300

Great cars will go forever. With horse power when needed. Check to see if it requires a timing belt. I think your year does not which means preventative maintenance should keep it going for a long time.
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Old Feb 12, 2019 | 10:43 PM
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Default Code popped

Okay the car is running great. Seems I was smoking out some oil that got into the cylinders while I was changing the plugs. The code that just popped is the cat code po420. I’m thinking it just has oil up in it. Thinking perhaps cleaning the o2 sensors which I can access easily. Aside from replacing the cat that is. What do you think? I’ve never had cat issues before until after changing plugs. Your opinion?
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Old Feb 13, 2019 | 12:49 AM
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Did you double check to make sure you have the proper spark plug gap? Also when moving things around you could have damaged something so inspect the PCV system hoses for cracks or any possible vacuum leaks as well as all 3 ignition coil connectors and wiring.
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Old Feb 13, 2019 | 10:21 AM
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Default Double checking

Checking all the wires. Look okay. Hoses look okay too. All I can think of is oil burned through the cat and perhaps is popping the 420 code. Is there a way to burn it off perhaps? Inspections not due until fourth month so I have to figure this out before then. I still think if I carb clean the o2 sensors. It could help. Any thoughts on that out there? I just don’t see the cat going bad just after I change the plugs. Ya know?
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Old Feb 13, 2019 | 11:31 AM
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I would never spray the o2 sensor with any type of cleaner, you can ruin them.
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Old Feb 14, 2019 | 11:01 AM
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Default O2

Cool. It was just a thought. Well to date the code has not come back on after ten miles of driving. Previously it came on after eight miles. The car is running smooth but does hesitate slightly a few times while driving. Like it burps. I think i will run a bottle of 104 plus and get on the highway get it to a hundred in the toll for a minute or two with no traffic of course. And a radar detector. Texas tolls are pretty wide open. Lol. Thanks for the advice.
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