C5 X7 random error

[silvering]

Hi guys

Haven’t posted in a while. I bought another X7 with 4HL engine (kept my RHR though). The car is in good condition, no errors no nothing. The engine is brand new (it had only 2000km when i bought it). As usual i did gearbox flush cause .. habits. I always use Febi oil covering the JWS 3324 specs. It didnt needed it, but it had some nasty kick shifting to D so i thought this will cure it for the next couple of thousand kms till i find good gearbox. On the way home from the garage i noticed it started shifting a little rough and somewhere near my house it threw U1209 in FAP app and went into limp mode. I pulled over, cleared the error, started the car again and all was fine. I’ve been diggin for the past hour and saw that its a communication error between the gearbox and the ABS ecus. Nothing specific. Does anyone hve any idea?

My VIN: VF7**************[VIN obfuscated, can be read by forum staff]

P.S. Where is the option to donate to the forum? Cant seem to find it.

[myglaren]

On the index page, lower edge of the banner, on the far left.

[GiveMeABreak]

Ok, so for U1209, the automatic box may start getting stuck in 3rd gear with the 'Gearbox Faulty' warning and you may also get the with ESP and Engine management lights up.

The Technical bulletin that deals with this issue puts id down to the electrical connections for the Engine ECU and the Automatic Gearbox ECU. Recommended action is to disconnect both these connectors and clean the contacts on the ECUs side and on the electrical harness side.

[silvering]

There was another error, for which i didnt remember the code, but it was stating ”random shifting” something. I don’t know why i didn’t mention it earlier. Havent touched the cable connections, but i will try them tomorrow after work (i hope it will get me to work). Also the weather is s**t, wet snow, so maybe that has something to do? I just changed the protection plates under the carriage, but still some water might have gone thru.

Which brings me to my next question. Im looking for another box and i read that boxes from RHH (and AHW) fits the 4HL if they sre with the pink nut next to the ecu. Can anyone confirm that? There are very few boxes from 4HL in Sweden and they cost over 1500€, but the ones from RHH are more in my budget.

[GiveMeABreak]

All I can tell you is that they have different part numbers between all the engines and different markings on the auto boxes.

[silvering]

I guessed that much, but it wouldn’t hurt to ask. Thanks for all the answers.

[silvering]

Also, i will ask here instead of opening another thread. The car doesnt want ro heat up. Till today i was with the original thermostat, never seen more then 73-74 on live data. Changed it with aftermarket one, noq it doesnt go more than 61-62. I live in Sweden so outside the last couple of days is chilly - around -5 till -8, but still. Im dealing with cars for 15 years and never seen something like that. Any ideas?