Car wouldn't start yesterday 1.4tdi BHC - DTC 17571 DTC P0183

A2_Stu

Member
Hello,

I fairly recently bought a 1.4TDi (BHC) and have had a few issues to iron out but the main concerns have been failing to start.

It's failed to start twice now - one appeared to be fuel going back to the tank - suspect fuel filter or tandem pump issue - no codes and worked when fuel was manually pumped through. This was a few months ago

Yesterday it failed to start and got the following errors When RAC scanned it:

DTC: 17571 Fuel Temperature sensor; open/short circuit to positive
DTC: Fuel temperature sensor A - high input......I think he said it was reading 117deg

RAC got it started using easy-start in the air intake.

Bit of background - I drove it about 440mile round trip to Santa Pod at the weekend. Seemed ok on the way down but on the way back I noticed it chugging a bit at tick-over and the rev counter dropped ever so slightly when doing it. Then used it for a few short journeys yesterday and when trying to start it after the 4th one it turned over but failed to start.

RAC man reckoned auto electrician might have to open wiring loom, look for broken wires etc but I was wondering if it might be either a break in the cable where it leaves the rear of the male connector as it seems quite tight or a fault with the sensor itself.

I've searched the site and can see there have been cases where the wires are visibly snapped but has anyone had a similar issue to this and it was a relatively easy fix?

I don't want to start throwing money at random parts if I can help it. Anyone know what the resistance from the temp sensor should be so I can test?

Thanks
 
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As I understand it, the fuel temp sensor helps the ECU to optimise fuel delivery but it's not critical. I believe that in the event of a zero/implausible value the ECU will default to using the coolant temperature. The wire to mine was broken when I first got it and it still started, idled and ran just fine. That said it did run noticeably sweeter after it got fixed. If the value is within range but high as per the RAC readout, you could try unplugging it to see if that makes a difference. If not, then it's probably not the issue.
 
As I understand it, the fuel temp sensor helps the ECU to optimise fuel delivery but it's not critical. I believe that in the event of a zero/implausible value the ECU will default to using the coolant temperature. The wire to mine was broken when I first got it and it still started, idled and ran just fine. That said it did run noticeably sweeter after it got fixed. If the value is within range but high as per the RAC readout, you could try unplugging it to see if that makes a difference. If not, then it's probably not the issue.
The thermostat needs replacing I believe so the temp gauge often goes up and down too.
I was thinking that a broken cable at the connector would lead to higher resistance - possibly giving the high fuel temp reading?

When I drove it home after getting it started it seemed to be smoking from the exhaust a bit.
 
Couple of things here
1 the fuel temp uses by the ecu will as already stated default to a standard value if the reading from the sensor is implausible It alters the calculation in the ecu for injection qty slightly depending on fuel temp but it will absolutely not stop the engine starting and running
2 be VERY careful using easy start etc on any engine It is evil stuff and very easy to damage an engine in a terminal way, bent con rods / trashed big end bears etc
The recovery services love the stuff because it gets an engine running if it is a fuel delivery problem and say a worn tandem pump the higher revs that the engine produces over and above the starter revs means that a worn tandem pump will pump fuel and the engine continues to run there fire the recovery service have got a car running again (but potentially knackered a perfectly good engine in the process)

The most likely cause is lack of fuel. Fuel filter change on the top of the list then check for air leaks a clear plastic pipe is helpful to look for air bubbles
If air bubbles then a leak needs finding and fixing. No air bubbles is fuel moving in the clear pipe. Yes then start to look at wiring to injectors. From ecu etc
If fuel not moving then tandem pump

The tandem pump as a hard life on the A2 as no lift pump to help it and it is designed to pump diesel not air so priming it is difficult. Use a vacuum pump to get the diesel to or near to the tandem pump
Also the bhc as the LUK pump which is not as good as the Bosch tandem pump and will also be 100,000 miles plus and 20 years of wear

Hope this point you in the right direction
This is one of the few things that fault codes don’t really help with

Paul


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Ironically I was going to order a fuel filter and housing before the car wouldn't start as it was my day off work. I've never noticed any leaks on the floor or around the tandem pump.

When the car wouldn't start yesterday, I hand pumped diesel through as I thought it might have been that but diesel was straight there. I'd just filled up too.

A little update.....
Thought I would test drive the car tonight before changing anything. Car started fine and drove fine, ticked over fine, no issues. After 10-15 mins car starts to warm up a little (temp gauge moves) and apparent slight misfire at idle again. Doesn't seem to be such an issue when driving but definite chug/misfire at idle, revs drop ever so slightly. Back to square 1, although car does at least start.
 
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If the fuel temp sensor is (intermittently?) duff - and the coolant temperature sensor is also (intermittently?) duff on one or both channels judging by your second post above, presumably at some point the ECU will run out of alternative plausible temperatures (if it is looking for an alternative to the fuel temp sensor) and will either give up completely or else use bad data which could in turn affect starting and running if I'm not mistaken.

Coolant temp sensor is one of the easiest and most tangibly satisfying fixes I learnt from here - I've done it 3 times now using various photos and tutorials on here - and would be a good place to start.

The fuel temp sensor is possibly even easier to replace if it is the one I think it is on the fuel pipes just in front of the tandem pump.
 
Ironically I was going to order a fuel filter and housing before the car wouldn't start as it was my day off work. I've never noticed any leaks on the floor or around the tandem pump.

When the car wouldn't start yesterday, I hand pumped diesel through as I thought it might have been that but diesel was straight there. I'd just filled up too.

A little update.....
Thought I would test drive the car tonight before changing anything. Car started fine and drove fine, ticked over fine, no issues. After 10-15 mins car starts to warm up a little (temp gauge moves) and apparent slight misfire at idle again. Doesn't seem to be such an issue when driving but definite chug/misfire at idle, revs drop ever so slightly. Back to square 1, although car does at least start.

Sounding more like a failing crank sensor. Ok when cold starts to fail as engine temperature (and crank sensor temp) rises
Unlikely to log a fault code until completely failed

Paul


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Thanks for all the replies, it's given me a few things to look at. I have a coolant temp sensor so will change that. Thought it was more likely to be the thermostat at fault to be honest. The rev counter always registered revs when turning over and failing to start so I thought that indicated a working crank sensor.
 
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It does indicate that the crank sensor is good but equally car starts and then goes off when getting warm which is classic sensor failure
When it would not start was the Rev counter showing revs on cranking. Likely around 300 rpm


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It does indicate that the crank sensor is good but equally car starts and then goes off when getting warm which is classic sensor failure
When it would not start was the Rev counter showing revs on cranking. Likely around 300 rpm


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Yes revs were showing when cranking.
 
Yes, which is why I kind of ruled it out.

The car's great when it's working right. Really need it to be working right so I can rely on it for work
 
Disconnected fuel temp sensor to see if it would run any different and it won't start again. Reconnected and still won't start. This is by now a cold engine. Gonna get Carista or similar ordered so at least I can do some kind of diagnostics. A job for tomorrow I think.
 
Connect a scope to it and check waveform. Should be a nice even square wave


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I know you don’t want to throw parts at it but I think you are at the point of needing to fit a new or known good crank sensor


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