Pre-purchase inspection, error codes P-1603 & P-1605

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Feb 6, 2019 | 06:38 PM

BobFur

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From: Ontario

Pre-purchase inspection, error codes P-1603 & P-1605

Greetings from Ottawa, Ontario from a wannabe GX owner.I am considering purchase of a particular 2010 GX460 with Ultra Premium trim.160,000km / 100,000 milesIt has lifetime service history from the selling dealership. I am negotiating this private sale with the original owner by phone as it they are about 5 hours away from me. Fortunately I know a trusted tech who's shop is near the vehicle's location. During his pre-purchase inspection, stored codes P-1603 & P-1605 were displayedThe CEL was NOT on.P-1603 indicates issue with TCU communicationP-1065 engine stall historyThe owner's story is that her GX has never displayed a CEL. She states that the engine has stalled, once only, when she walked away from the GX with the key in her pocket while it was idling on her driveway.That explanation does not seem plausible unless, maybe it is programmed to shut down when idling in Park if a door is open and the key wanders away. (?)Also, if the vehicle does shut itself down through a timer or whatever, that should not trigger an error code. Right ?I would appreciate comments from those having experienced codes P-1603 & P-1605 and what issues were diagnosed and how they were resolved.I have looked through the online owners manual and could not find anything about the engine switching off when left idling in Park with a door open in absence of the electronic key.Anyone have knowledge of that matter ?Thank you

Feb 7, 2019 | 08:08 AM

cancruiser

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From: AB

As far as I know, these codes (P-1603 & P-1605), are common and do not pose any issues. They usually occur when the battery is disconnected and then reconnected again (perhaps new battery was installed).
When I purchased my truck a few months ago, my mechanic (well versed in Lexus/Toyota) saw the same codes and said it is very common..

Feb 7, 2019 | 10:29 AM

coolsaber

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From: In your head

Besides those codes what did your PPI come back with? Service history? Body Condition (including undercarriage)?

Those can assess a complete picture on the vehicle.

Feb 7, 2019 | 10:45 AM

cancruiser

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From: AB

What your mechanic should do is to clear the codes history, take the car for a test drive then see if the codes return. Most likely they won't..

Feb 7, 2019 | 03:11 PM

BobFur

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From: Ontario

What I have learned......
The most likely cause of the stored codes was changing the battery without using a OBD "memory saver" device.
Apparently it is common for Toyota/Lexus vehicles to loose throttle body idle settings when the battery is disconnected.
This may lead to engine stalling until control modules re-learn settings for the throttle valve idle circuit . Hence the engine stall code.
The owner reported that a new battery had recently been installed. Presumably by someone unaware, as I was, concerning use of a memory saver device.
This also explains her report of the engine having stalled while idling on her driveway.
This GX checked out fine otherwise But I was put off buying it due to chassis rust.
Guess I simply had not seen the underside of an older rust belt vehicle in a while. Yuck !
Top side looked very nice in all original paint.
Will resume my GX search in Florida next month
They are significantly more $$$ in the USA but at least I should be able to locate one with a clean chassis.
Thanks to all who contributed suggestions & advise !

Feb 7, 2019 | 03:22 PM

cancruiser

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From: AB

One year driving in almost ANY city in Canada and the chassis will look like this and worse.
But, of course, if you can source another truck from any of the southern states, that will be great. Also trucks from BC seem to have much less rust. I saw a couple around here for sale, but didn't buy them because they were offered by dealers (I never buy from dealers)