thisgtaguy

I have a GS 450h 2008 with about 140000KM. The Hybrid check engine light turned on about 6 months ago. I managed to download and install the TechStream software and read the error code shown as (P0A7F-123 Hybrid Battery Pack Deterioration). But the battery charges pretty well according the TechStream Software (attached is a screen shot). If I erase off the code the car runs fine for a about 60-100km and then turns on again. I have opened the battery and checked each cell one by one and put load on them. They seem to charge well and resist under the load. What could be issue?

I have included the Freeze Frame Data for the P0A7F error, in case someone can help me point out what the issue is here.

Mlig

I got GS450H 2009 with 130,000KM with P0A7F error code that comes and goes away. Did you take to Lexus service?

thisgtaguy

Mlig,
I did not take it to Lexus. I have the car with me in Dubai and the Lexus dealership here does not want to service any imported car from North America. So I had to buy the TechStream Software and the cable and do the diagnosis myself. I have even opened the Hybrid Battery myself and checked every cell individually but has not been able to find any issues. I am suspecting this problem is caused by a faulty sensor or wire. But I can't find it. If you have any clue please share.

Mlig

I am electrical engineer and I know voltage test works when there is a real issue with battery. The best way is to test it under load all at the same time and measure voltage for each cell before and after test. If not that easy for you to do so. Connect a 12Volt 20W bulb for 3 minutes to each cell and write down the voltage before and after, That will tell you which ones are not happy.

thisgtaguy

Miig,
Thank you for the reply. I have actually tested each cell one by one, putting load on them. This was done with the help of an electrician. All cells seem to hold the strong. I suspect this has to do with some faulty wiring or censor. But I can't seem to find it. Every time I clear the error code it comes back in 2-3 days in random situations. Not sure how to diagnose it.
If anyone can shed some light and help out here I would appreciate it.

Mlig

If you had a faulty wire, the result would be random. It can't be the same all the time. It cab be battery contact corrosion but I am sure your electrician cleaned them all. The easiest way is to turn on the engine while the heater is on and use insulated gloves and move or bend connecting cables to see if they have loose connection. Also make sure temperature sensor wires are connected properly. It is possible that your battery ECU is in trouble too. The battery smart unit is an electronic control unit (ECU) that monitors information, temperature, and voltage of internal battery cells. The battery smart unit ECU processes information and then sends it on to the hybrid vehicle ECU (HV ECU). If you can barrow a used one and replace yours to see if that solves the issue or not.

thisgtaguy

Mlig,
I REALLY appreciate your help here. So thank you!
Well, the mechanic did not clean the corrosion, that I am sure of.
As for the ECU, I suspect the same. But unfortunately, there are not many Hybrid cards of this type here in Dubai, since I shipped my car from Canada to Dubai. I am going to open the battery this weekend again to check on the wires and the ECU. I will post the update here.

thisgtaguy

Mlig,
Cleaning the corrosion did not help. I keep getting the random codes starting with P0A7F. I believe it is the Hybrid ECU. If I replace this with a used one do I need to re-program it?
I have read several post where people had problem starting the car after replacing the ECU. Can it be reprogrammed using TechStream software?

samsonn25

Sounds like a possible electrical or ecu issue. If the car runs fine I would not worry too much.

I have the check hybrid system light go on every 4 months but it goes away after 2-7 days

I have had this code in my history on techstream but erased it. . It was described as intermittent on off.
My hybrid battery charges fine I have 7 out of 8 bars. . I have 196k miles on original traction battery.


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thisgtaguy

Thank you @samsonn25. I get 2 codes. P0A7F and P0A80. The P0A7F comes more frequently and does not affect how the car drives. However the P0A80 code comes every 2-5 weeks and it affects the way the car drives. Once that code comes the car misfires or jerks when up/down shifting.
I have purchased a used ECU. I will replace it and see how it goes.

ahxun

Following, curious to find out before getting one (from grey importers), as local Lexus dealership do not carry this model. Hybrid battery is my biggest concern.

thisgtaguy

@ahxun what are you trying to get from "from grey importers"? Are you planning to replace your ECU?
I have not gotten a chance to replace mine. Once I do, I will post the result here.

BULLITT1

found this bulletin online, hope this helps. looks like a ecu update.

thisgtaguy

@BULLITT1 Thank you very much. This can be a big help!

BULLITT1

Glad i can help. New to this forum, not to lexus.