D40 auto torque converter

[harryx5]

Hi guys,

My check engine light came on while doing a few thousand kms over the Christmas holidays. I had a country dealer do a quick diagnosis while I was away.

The error code is P0744 and is to do with the torque converter not locking up.

My question is: how/when does the torque converter lock? I'm doing some more highway driving soon and want to fully understand the issue before I book the car in for repair. I can't really notice any lockup, maybe that's because it's broken! My fuel economy was disappointing too, which would make sense.

It's a 2013 Spanish built D40 ST, less than 10,000km on the clock.

Cheers,
Harry.

 

[Old.Tony]

In the older cars (like mine) with the 4-banger diesel, they lock under the following conditions:

* Gear selector in D
* Overdrive NOT disabled
* Vehicle speed 75km/h or higher
* Engine load below 50%

You should find that your RPM at 95km/h drops to around 2,000.

If you have the V6 diesel, the parameters should be similar except the engine RPM at that speed should be around 1700.

 

[JPMC]

The lock up on the later models is slightly different to what Old Tony has discribed with the fact that the later model autos will lock up in 2nd,3rd,4th and 5th/D.
I can't remember off the top f my head at what rpm but as stated by Old Tony at around 95-100km/h with the converter locked up you should be sitting at around 2000rpm.
When the converter is slipping it increases the rpm by 300-500 depending on the gear and driving conditions.

Hope this helps.