Guidance Request GX470 (1 Viewer)

Joined
Jan 9, 2021
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Central Virginia
Reaching out to those of you with more knowledge and experience. I have a 2004 GX470 that I've owned for just over 6 years. Purchased with 100K miles - now at 222K. She's been a great vehicle - only expense to date has been tires, brakes, CV axles, timing belt and rear differential noise fix. Last summer she pulled our 26' travel trailer 6000 miles out to Wyoming, Utah, Montana, and back to the East coast. Wondering if I should hold on to her. My wife is after me to make the 'christmas tree' lights on the dash go out. For the last 2 years the following lights have been on - VSC, TRAC, TPM, and Check Engine lights. The codes are: Fault in ABS C1223, C1252 Hydroboost motor fault, Catalyst system P0430 and P0420 (Catalyst System Efficiency below threshold bank 1 and 2).
I'm a school teacher, so not a lot of extra money to slap down $2000 plus on Lexus OEM parts or service.
Questions:
1. Has anyone tried the Bosch conversion for the brake issue? (Not sure if this option eliminates motor, accumulator, issue or if it's a non-starter) $450 - Only noticeable symptoms are when the weather turns colder - pump cycles and beeps until warmed up - brakes seem to work fine. On very rare occasions (3 times in past 2 years), the ABS warning light and alarm come on when the car is first started - but goes off after a few minutes. I understand 4runner parts are interchangeable - maybe find used parts in local junk yard??
2. Check engine is due to Cats or O2's. Haven't tried changing O2's yet - would it throw a different code if it were as simple as replacing O2 sensors? Is it worth it to replace cats? Any after market products anyone would recommend? Shop quoted me over $2000 for OEM. - again, I've been driving it like this for over 2 years without any noticeable brake or performance issues - even when towing 6000# trailer over 11K elevation mountains out west.
My wife really loves the vehicle, and I know they are well built and highly capable for off-road needs. My main worry is if something major breaks and then it becomes a big paper weight that I can't afford to fix. The vehicle is in great condition - no accidents, no rust- leather still super clean, etc. Only body issue is that I recently noticed a small patch of paint flaking off the roof (about the size of my fist) Pearl White.
Any help / suggestions would be much appreciated.
 
Joined
Mar 28, 2020
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Texas
If the vehicle has been good to you and you've got the full service history (especially after having it ~120k miles yourself) I would keep it and fix it in a nanosecond. They just don't make vehicles like this anymore other than the brand new GX, but technology = booooo. Ask yourself how long the vehicle has been paid off and how many months you've saved on car payments. The likelihood of something major breaking would of likely of happened already at ~222k miles. If the drivetrain and suspension are in good shape I doubt you'll have a major problem in the near future if the vehicle is taken care of. How was the first 120k miles from the previous owner(s)? Was its service history good before you bought it? Sorry if I'm being long winded, its just the way I am. I like being overly thorough.

1. I haven't done this, so I'll defer to someone else who has as my '08 470 doesn't have this issue. Have you 100% diagnosed what exactly is causing the issue? That would go a long way in determining the course of action needed and where you can save some $$$. Have you priced out the replacement parts using aftermarket replacements? OEMs will be expensive.
2. Buy some cheap aftermarket but not junk cats and some new OEM O2 sensor(s) online, you'll be fine. OEM cats are always going to be very expensive, an aftermarket cat is just fine.

As far as the paint issue, well that's going to be something to watch. If you've got the skills and equipment I recommend going ahead and Raptor coating it now before it gets substantially worse. Even with modest painting skills and equipment you can have brilliant results coating it yourself. I plan on tackling this myself for both our GX's.
 
Joined
Jun 11, 2019
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TDY
2 years with Cat codes? Wow. Could have been just sensors, but the Cats may be cooked now. Who knows, needs to be diagnosed.

The ABS codes are probably a pump failure, but then again needs to be diagnosed.
 
Joined
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Check engine is due to Cats or O2's. Haven't tried changing O2's yet - would it throw a different code if it were as simple as replacing O2 sensors? Is it worth it to replace cats? Any after market products anyone would recommend?

Read up on 'spark plug anti fouler' for your oxygen sensor P0420 code. It's the $9 fix for the problem - the short version is that you drill out a spark plug anti-fouler and install it on the REAR oxygen sensor, which makes the sensor less sensitive and thus alters its output, which is just what the computer is looking for, and this prevents the code from returning. This is commonly done on many US and foreign vehicles. A shop might be reluctant to do this and a dealer won't (for emissions reasons). It's an easy DIY if you're handy. You will never feel a P0420 code nor will it affect mileage, performance, etc. It's simply a code where the computer isn't seeing enough difference between the front and rear oxygen sensor outputs and concludes your cat converter isn't doing much.
 

IanB

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Fixing is likely far cheaper than replacing, but as vehicles get older they do require more fixing. Would you rather fix and save some money, or replace and have a car payment every month?
 
Joined
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Fixing is likely far cheaper than replacing, but as vehicles get older they do require more fixing. Would you rather fix and save some money, or replace and have a car payment every month?

It’s funny, I generally recommend people save up a monthly cost of a modest car payment and put it in to a savings account that can be used for repairing their paid off vehicle when repairs come up. It helps with situations like this and others more severe. Older vehicles do need more maintenance but worth it in my opinion to keep them and fix it if it isn’t something like rust or a complete drivetrain failure (haha).
 
Joined
Jan 9, 2021
Messages
4
Location
Central Virginia
Check engine is due to Cats or O2's. Haven't tried changing O2's yet - would it throw a different code if it were as simple as replacing O2 sensors? Is it worth it to replace cats? Any after market products anyone would recommend?

Read up on 'spark plug anti fouler' for your oxygen sensor P0420 code. It's the $9 fix for the problem - the short version is that you drill out a spark plug anti-fouler and install it on the REAR oxygen sensor, which makes the sensor less sensitive and thus alters its output, which is just what the computer is looking for, and this prevents the code from returning. This is commonly done on many US and foreign vehicles. A shop might be reluctant to do this and a dealer won't (for emissions reasons). It's an easy DIY if you're handy. You will never feel a P0420 code nor will it affect mileage, performance, etc. It's simply a code where the computer isn't seeing enough difference between the front and rear oxygen sensor outputs and concludes your cat converter isn't doing much.
Really appreciate the tip - I've never replaced the O2' s - I was told that the diagnostic tool would throw an O2 specific code if that was the problem. Would you recommend trying the anti-fouler first, or replacing the O2 sensor(s) first? Thanks again.
 
Joined
Jan 9, 2021
Messages
4
Location
Central Virginia
Appreciate the advice and thoughts on benefits of setting aside money to maintain older, quality made vehicles. I'm a school teacher with 2 teenagers - so by default, I have to be cost conscious. I was hoping someone else out there had some experience with the hydroboost / brake pump issue:( I've seen a you-tube video on the change out and it doesn't look too bad. Just not sure about pick-n-save / ebay parts over oem options.
 
Joined
Dec 14, 2020
Messages
161
Location
Missouri
Replacement Denso downstream O2 sensors are $40 each on RockAuto. It's not uncommon for O2 sensors to loose functionality after 10+ years. I would recommend replacing the O2 sensors and seeing if that makes your PO420 codes disappear. If not, you have another problem (potentially an exhaust leak or the catalytic converters themselves) and you could either replace them or use the O2 sensor spacers. I personally like clean air and well-functioning cats, so IMO opinion it's preferable to find the actual problem and rectify it. The O2 sensors are not hard to replace with a sensor socket that an auto parts store will rent for free.

For what it's worth I had an older Subaru with a chronic P0420 code and P0302 code (front O2 sensor) that I could not get rid of despite new sensors, new cats, and even the anti-fouler. I finally suspected it was the wiring and hard-wired the front O2 sensor into the car's engine harness and bypassed the connector. Both codes disappeared immediately after that and never came back, indicating the connector had a poor connection in it.
 
Joined
Jan 9, 2021
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Central Virginia
Good information - much appreciated. Anyone have any guidance on the brake issue? When I start the car in winter months, intermittent squealing sound coming from brake booster area - suspect its the hydro pump eventually stops, and I do not notice any issues with brake function.
 
Joined
Oct 27, 2009
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outer space
Check the 100 series forum. There’s tons of information on the brakes. Seems like a problem - they’ve got a poll going on brakes failing. Yours might fail so be careful, indicated by the xmas lights on the dash. Read everything on the brakes by @2001LC he knows his stuff and is very very detailed oriented. I’m pretty sure our brake system is identical and have been meaning to check mine per Paul’s (2001LC) test methods. I’m a little surprised we haven’t heard of more problems with our GXs - but maybe I just haven’t been paying attention.

let me know if you can’t find the threads over in the 100 / lx470 section.
 
Joined
Dec 15, 2020
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Gonzales, LA and Gunnison, CO
Here's a tip if you think a connector might be causing a problem, clean the connector tips with Deoxit before you replace or bypass it. It might solve your problem. Oxidation causes lots of problems especially when a computer is looking for a tiny voltage or amp difference.
 

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