Technical P1851 Gear lever position sensor

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Technical P1851 Gear lever position sensor

Joined
Aug 18, 2023
Messages
6
Points
29
Location
Germany
Hey everyone,

my problem Fiat is back at it again. After getting my starter motor replaced, sometimes my power steering would not engage. It did this like two or three times, took a restart and it worked. Haven't had this issue the past few days.

Today after getting a headlight replacement, I went to my local part store to check for the bulbs I need. Came back, turned car on, check engine light with the yellow triangle, car ran fine tho. Drove home, grabbed my OBD scanner, and got P1851 Manufacturer specific code.

Looked it up, according to the internet, it is the Gear lever position sensor. I haven't had any problems with this before whatsoever, so I just cleared the code and went on my way.

It returned later, except this time with the red battery symbol. I restarted the car, battery symbol went away. Cleared it again, drove half a mile, it came back. Sometimes it is with the battery symbol, sometimes not. What could the issue be, what should I look into first?

I feel like this mechanic pulled a connector to get me to spend more money, after overcharging me for the headlights he tried upselling me new tires and springs (springs were changed two years ago and look brand new). I believe he may have done something to get me to blow more money on his shop. First thought this could be related to me disconnecting the battery (to ease access to the bulb housing), but I don't believe it could be from that.

What should I look at first? Maybe try checking connectors (where are they located related to this), swap out something etc.

Shifting etc. works without problems, only start stop is permanently off (which honestly I love, excluding those two warning lights).

Thank you!
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Model
1.2 69 PS Dynamic
Year
2011
Mileage
158032
There is a Neutral position sensor on one of the shifter cables, below the gear lever. It tells the Body computer when gear is in neutral, so it enables start-stop. This sensor needs calibration by Fiat Examiner or MES, if the battery or the ECU is disconnected. Your mechanic might disconnected the negative terminal and also damaged the cables leading to the battery node on the negative pole. Finally, i would check the condition of the ground on the other end of the negative terminal, it's right below the battery and might is corroded...

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There is a Neutral position sensor on one of the shifter cables, below the gear lever. It tells the Body computer when gear is in neutral, so it enables start-stop. This sensor needs calibration by Fiat Examiner or MES, if the battery or the ECU is disconnected. Your mechanic might disconnected the negative terminal and also damaged the cables leading to the battery node on the negative pole. Finally, i would check the condition of the ground on the other end of the negative terminal, it's right below the battery and might is corroded...

View attachment 460403
I've cleaned my ground points and my mechanic has also done that, and has inspected the negative terminal wire, said they're fine.

I will ask the other mechanic that has done my headlights what he did.

Regarding calibration, this is the first time I've encountered this issue, and I have swapped batteries/disconnected this dozend times. Would I need MES Registered? And do you maybe have a clue how I can calibrate it with MES? I have nobody local with MES, although I have the free version myself, and if needed I can buy the Registered one.
 
MES-Engine-Adjustments-Neutral position learn. An yes, MES needs to be registered. But then again, if your mechanic has a decent OBD diagnostic tool, it should do it too...
 
MES-Engine-Adjustments-Neutral position learn. An yes, MES needs to be registered. But then again, if your mechanic has a decent OBD diagnostic tool, it should do it too...
My mechanic is a private one, he's cheap, does his job perfect & quick, sadly got no diagnostic tools tho.

And I am absolutely not going back to the guy that did my headlights lol

I'll look into getting MES registered
 
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