P0128

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Oct 25, 2025 | 03:49 PM

ConcertBoy

Thread Starter

Junior Member

Joined: Jul 2025

Posts: 26

Likes: 13

From: Newbury Park Ventura SoCal

P0128

This came up while shifting to sport mode on tight turns.
2009 XKR 4.2.
regards

65k miles.
I Read previous posts
I added a cup of coolant and cleared the code.
will drive for awhile and see if it comes back.

Last edited by ConcertBoy; Oct 25, 2025 at 04:26 PM.

Oct 26, 2025 | 10:46 AM

guy

Veteran Member

Joined: Apr 2008

Posts: 3,683

Likes: 1,678

From: Ottawa, Ontario, Canada

The common root causes for that code are:
1. Fluid is no longer in operational spec. Change the fluid.
2. Thermometer has deteriorated. Change the thermostat.
cheers

Oct 26, 2025 | 02:44 PM

Sean W

Veteran Member

Joined: Jun 2013

Posts: 8,936

Likes: 4,743

From: USA

Quote:

Originally Posted by guy

The common root causes for that code are:
1. Fluid is no longer in operational spec. Change the fluid.
2. Thermometer has deteriorated. Change the thermostat.
cheers

My two cents. Do both