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Fault code U0401?

Posted: Sat Jan 12, 2019 1:36 pm
by jstanovic
2 days in a row now my Ranger has thrown U0401 error code (see pic below).

Started my car first thing in the morning yesterday, it idled for about 1min then drove out my street as I do every morning. Lots of short curvy streets around here so I just take it easy so 1500-2000rpm max and 3rd gear tops (auto trans). Got less than 500m from my place and the change into 3rd was more like a small thump, then 5 secs later the stability control light came on and stayed on (no other lights). It then seemed to lock into 2nd/3rd gear but otherwise drove fine. Went back home to get my Forscan bits, got the code in the picture below. Restarted the car and the light went off and drove perfectly for the rest of the day, no more dash lights.

Exact identical issue this morning, again I turned it off the restarted and was all good, did about 50km with no issues.

Gearbox was flushed about 10,000km ago and no issues until yesterday. Tranny guy does work for the local Ford dealer so he knows these in and out and hopefully used the right fluid.

The code mentions ABS (dirty sensor?) but why would the tranny thump into 3rd then go into limp mode?

Any ideas??

The other BCM fault is just the sports bar light missing
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Re: Fault code U0401?

Posted: Sat Jan 12, 2019 4:37 pm
by saeb
I was working on one yesterday for about 3 hours with this exact same issue. I have yet to come to a conclusion on what the problem is. Either some wires rubbed through where under the fuel filter area to PCM or a faulty PCM is where I'm at, at the moment.

I'm getting one additions U0401 from the TCM also.

Its not canbus related. It is not relay or fuse related.

Will let you know if it gets sorted.

Check top intercooler pipe for any splits properly also.

Re: Fault code U0401?

Posted: Sat Jan 12, 2019 6:38 pm
by jstanovic
Will do. It was replaced about 3months ago so hoping it’s not an issue.

Re: Fault code U0401?

Posted: Tue Jan 15, 2019 1:50 am
by jstanovic
Well today it happened for the 3rd day in a row, but after I restarted it it happened again a 100m down the road and the engine check light also came on. Forscan tells me there is an EGR fault, plus a few new codes too. Cleared the codes and went on my way. Car sat for 6 hrs and when I restarted it was fine, not an issue in the 60km I drove today. Checked with Forscan when I got home, no codes at all.

I was contemplating getting a tune done and heard that they can tune out the EGR.
Will that solve this issue?
Can that be done on a PX1?
I would rather spend the cash on the tune in the first place rather than replacing the EGR valve and then getting a tune later.

I checked the top intercooler hose and connections, all looks good.

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Re: Fault code U0401?

Posted: Tue Jan 15, 2019 9:05 pm
by saeb
I think you are right. It is buggered.

So I rang my mate today to see where that PX1 was at. Further talks with the owner reveal it has a tune.

I bet if he removes that tune and it will happen then he may get the rest of your codes also.

I say fix it before you tune. Why cover up a problem that could make things worse.

Re: Fault code U0401?

Posted: Wed Jan 16, 2019 1:49 am
by jstanovic
I spoke to some tuners today and they reckon they can block the egr, bypass the water pipes and tune out the egr as long as the water hasn’t cracked into the gas side.

Re: Fault code U0401?

Posted: Mon Aug 26, 2019 6:15 pm
by barker
Did anyone solve thus have same problem

Re: Fault code U0401?

Posted: Tue Aug 27, 2019 10:25 pm
by jstanovic
I got mine checked out and tuned at the same time. Turns out the EGR was stuck closed, the tuner deleted it from the ecu and I've had no issue since then.