Hoping you can provide some help.

I read one of your posts about BMW Transmission and just left a comment, asking the same, then saw you had a section where I can ask a question.

 I’ve had an issue with limp home for 2000 E46 323i.

What occurs is that if the Air Con is on and I come to a stop (eg at a traffic light or stop sign, etc) the gear symbol comes up in the dash and transmission goes into limp home mode.

If I have the Air Con off there is no problem, or, if I turn the Air Con off before stopping again no issue.

The issue seemed to have commenced after a mechanic replaced the radiator fill bottle and hoses due to a crack in the bottle, I’m not sure he replaced the transmission thermostat at the base of the bottle or not. I had initially thought this may be the problem as it is difficult to replace the bottle without cracking that thermostat, I understand if that thermostat is damaged you get the limp home happening as well. However, as above I find limp home only occurs if Air Con on at time of stopping car.

Any thought would be appreciated.




Hi Mark. 

Most likely there is no problem with your transmission. There may be an issue with the cooling system that the car things is critical and puts the car into limp mode

What you need to do is read the codes from these modules and see what codes you get. There are a few scanners out there that allow you to do a full system scan on BMWs. 

Start with that and let us know the codes. 

Hi MercedesMedic

Have you had a chance to check the codes I posted.

Thanks for your helo


I think a cooling system problem is throwing your car on limp mode. The car does it when you turn on the AC because the radiator fans always turn on with AC on. 

Have you scanned for codes yet? 


I don’t have a scanner at the moment, trying to find one that is useful for BMW to find all codes, etc and not overly expensive, when I do, I’ll put in the details.

If you have a suggestion, let me know

The Foxwell ccanner just arrived yesterday (took a couple of weeks), so hoping I'm using it correctly, scanned for codes with ignition switch on to position 2 (dash lights on, engine off) and scanned for codes.

As before, if car is started and in gear with Air Con ON, the "gear" indicator light will come on, if the car is switched off then turned on again put in gear and with Air Con OFF, then no issue.

I wanted to try and do a live scan when the limp mode light came on, but wasn't sure how to do that yet, nor what parameters to look at as yet, need to read manual a bit more, unless you have some tips in that regard.

The codes that came up are as follows:

DME: Signal exhaust-camshaft sensor (OBD II P1397, EUIII P0340)

DME: Fuel trim bank 1 control limit (OBD II P0170, EUIII P0170)

DME: Fuel trim bank 2 control limit (OBD II P0173, EUIII P0173)

EGS: Stall speed (P0720)

KOMBI: Tank lever-type sensor 2

LSZ: Activ'n motor for headlight-range adjust 1

LSZ: Activ'n motor for headlight-range adjust 2

GM: Power window: motor or relay driver, rear

GM: Windscreen washer pump

GM: Boot-lid unlocking mechanism




Hi Jeff

Have you had a chance to check the codes I posted.


Thanks for your assistance



I would look at Foxwell NT510 for BMW 

This would be a good start: https://www.youcanic.com/guide/obd2-scanners-bmw

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