P1600 Trouble Code

[JRohrer]

Hello, I am new to the forum as I just purchased my 1995 LS400 a couple of months ago. Both my wife and I really like it, but we have one problem. The check engine light came on. I took it to Auto Zone and they pulled the codes. The codes were P1600, P0420, & P0430. I checked the code names on this site and came up with: P1600 ECM Batt Malfunction; P0420 &P0430 refer to cat being below threshold. My question is "what does EMC Batt Malfunction" mean? Is it somehow connected to the cat threshold problem?

I really want to get this taken care of as soon as possible, so any answers would be greatly appreciated.

Thanks,

Jon

[blake918]

Jon, welcome to the club! Here's some info on the P1600...

[JRohrer]

Jon, welcome to the club! Here's some info on the P1600...

Blake,

Thanks for the info!!! I was wondering if you or anyone else has seen this type error code before? I have wrenched alot on different vehicles, but never ventured into the computer end of it. I will check the voltage between the ecm batt and ground and check the EFI fuse. Hopefully I'll find the answer.

By the way, I think your car and mine are identicle twins. Sure is a nice looking car!!

Thanks,

Jon

[blake918]

Jon, I have not had this code on my car. Hopefully it's just the fuse, and not the computer! You're right, we do have some good lookin' cars! Let us know how this turns out.

[Buckaroo]

I have a 1995 LS 400 with 215,000 miles. Vehicle runs fine.  It shows a check-engine light with code P1600. I need help to turn off the check-engine light. Coming up on smog check and it won't pass with check-engine light on.

Thank you!

[paulo57509]

12 hours ago, Buckaroo said:

I have a 1995 LS 400 with 215,000 miles. Vehicle runs fine.  It shows a check-engine light with code P1600. I need help to turn off the check-engine light. Coming up on smog check and it won't pass with check-engine light on.

Thank you!

DTC P1600 = ECM Battery Malfunction

Essentially, the DTC is telling you that the ECM has lost the +12 volt supply.

I don't have a '95 model year manual for reference, so I'm not going to tell you to start probing around with a volt meter.  However, you can check the fuse panel and of there's a fuse labeled "EFI No. 1" and check to see if it's open (blown).  You can try replacing it but keep in mind, you still need to determine why the fuse blew in the first place.

[sha4000]

On 2/6/2020 at 2:10 PM, Buckaroo said:

I have a 1995 LS 400 with 215,000 miles. Vehicle runs fine.  It shows a check-engine light with code P1600. I need help to turn off the check-engine light. Coming up on smog check and it won't pass with check-engine light on.

Thank you!

Did you do the check in the second post of this thread? Also I would remove the ECU and check the capacitors.

 

https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/656360-all-my-crazy-lexus-issues-solved-ecu-leaking-capacitor.html

[Ashus]

I have a 95 that has the same problem but I am about to replace my computer because after driving for 6 months the car is starting to act up it won’t let me go over 2000rpm starts yo misfire after that and some time it starts to dump fuel in the engine Idk what’s wrong I thing it’s my computer