P1128 CEL Code - Throttle control issue

[CanadianRockyCruiser]

Hi Guys,

Looking for some help/advice here. Let me explain the symptoms:

I left the office today and tried to start my 2001 LX470 with the remote starter. It shut off pretty quickly. Got out to the car, it's -30 degrees Celsius (-22 F), and the car won't start. It cranked just fine, but wouldn't start. I plugged in my ODB2 diagnosis tool, and it reads the P1128 CEL code.

Went inside the office to do a quick search and couldn't find much on the issue. I came back to try again 10 minutes later, and the CEL light was on, LX started up first try, but had a strong fuel smell coming from the exhaust. When I got home the fuel smell was gone

I'm wondering if anyone else has experienced this issue. It might be a problem with the Throttle control motor, but I'm not sure. Perhaps an injector failure? Perhaps an issue with -30C temperatures... Thought I would check with you fine folks before taking her to the stealership, for diagnosis and wallet-rape.

Thanks in advance for any help or advice.

 

[Sandroad]

I'm not sure about the affect of the remote starter on the issue. I have certainly seen on other forums a lot of posts about problems caused by remote starters over the years. Regarding the P1128 code, I have not had the problem and can't directly help, but there are at least 9 other threads with over a 100 posts that pop up if you do a search on MUD with that search term. Here's one:

https://forum.ih8mud.com/100-series-cruisers/166808-p1128-throttle-control-motor-malfunction.html

 

[marshotel]

It sounds like a temperature-related issue to me.

Mine cranked but would not start a few times when it was really cold. Charging the battery with a jump pack or jumper cables always made it start, even though it sounded like it was cranking fine before the jump.

Likewise, my exhaust always smells gassy at first when it is that cold outside.

I think the engine runs in "open loop" mode until the O2 sensors come up to temperature. As a result, the air/fuel mix is extra rich during the warm-up period and some unburned fuel gets passed to exhaust until the engine warms up.

In addition, cranking it for a while before it starts would contribute extra unburned fuel to the exhaust during the first few minutes.

In summary, I would not worry about it too much. Check the battery first. At 30 below zero, it takes a really good battery to start the engine, even if it sounds like it is cranking fine.

I would clear the code and replace the battery, and hope that fixes it.
I bet everything will be fine once the temperatures warm up a bit.

 

[12guns]

Have you checked the throttle body? Seems a lot of the cel codes that involve throttle position sensors and such often are gunned up and just need a good throttle body clean out. Mine was acting up in the first cool weather we had after it sat for a couple weeks. It started but after 10 miles of driving, when in r&e started it, I got an wakeful clunk and was sent into limp mode. A restart cleared it up but the cel was still on. Throttle position sensor was my code. A cleaning helped and it hasn't acted up since. That may not be your problem, but for a 10 min cleaning,MIT might be worth looking into.

 

[CanadianRockyCruiser]

Hi Guys,

Thanks for the recommendations. I cleared the code from the system and have put on another 100km since then without the code re-appearing.

I believe the issue was due to temperature; perhaps in a few ways.

1.) The remote starter is programmed to crank minimally on the first attempt, and in greater increments of time (cranks) for any subsequent attempt, should the first attempt be unsuccessful.
2.) I had parked near a large truck's exhaust (International durastar), which would have put a lot of exhaust and water vapor right near the front of my truck. This may have caused some freezing under the hood.

I will continue to monitor the system for any uncharacteristic behavior, but for now, I'm satisfied that this issue was related to extreme cold, and all of the nuances that come along with a Canadian winter.

Thanks again for your thoughts!