P2127 code on a Focus XR5/Focus ST

I had an issue with my 2007 Ford Focus XR5 (aka Focus ST) recently.

I started getting a ‘Steering Assist Failure‘ message appear occasionally when starting my car. Usually I could just turn if off, leave it for a little while then start again and it would be OK, and the car would be behave normally.

Shortly after I got an ‘Engine Systems Fault‘ message and the car entered ‘Low Acceleration Mode‘ to protect itself. Using my OBD-II adapter and the ‘Torque’ Android app, I found the specific error to be:

P2127 – Throttle/Pedal Position Sensor/Switch ‘E’ Circuit Low

Using the magic powers of Google, I found this:

“Finally the P2127 error code was sorted.

When the car is started in the morning the voltage drops below 9v.

9v is the threshold voltage for the all the ECU sensors, first sensor on my car that then schemes there’s k@k in the land is the throttle position sensor.”

Using my very cheap multimeter, I tested the load across the battery. When I turned the key, sure enough, the voltage dropped from 12.43V to 8.3V, sending the throttle position sensor into an error state. Testing the same thing on Bek’s car showed it dropped to about 10.5V which is much healthier.

Once I installed a new battery, everything worked perfectly.

Hopefully this might help someone else, although I’m sure a different type of car would exhibit different symptoms.

Posted in Personal by Andy Botting at March 28th, 2014.

5 Responses to “P2127 code on a Focus XR5/Focus ST”

  1. mike blewett says:

    Hey Andy,
    Weirdly enough got a similar error on my Mk5 golf and, yes, my battery is on the way out too. Time to get a new one me thinks.

  2. Vince says:

    Thanks Andy – just had much the same problem on a 2006 ST – I got P2127 throttle position indicator – came up a few times intermittently (always on starting) and cleared if I switched on and off. Ultimately died on me and turned out to be a knackered battery – now replaced and everything is fine.

  3. Charlie says:

    I am getting that code. Funnily enough when i turn the ignition its geeting slower to crank over.

  4. Dave says:

    Im having exactly same issue I’ve replaced battery even upgraded to a Bosch s5 and its still occurring could this now actually be the tps that is cooked ? Im going nuts over this now its been about 2 weeks on and off I’ve even gone into limp mode deep into a drive in heavy traffic it was not fun …maybe time to swallow pride and take to a ford garage or specialist

  5. Russ Spencer says:

    I had similar problem on my Focus ST 3 2006 showed engine fault reduced acceleration when I started it. New battery has sorted it!

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