Yoda the Skoda just decided not to start one morning. I did some troubleshooting and gave it to the garage but no joy. They suspected the ECU. So before scrapping any ideas would be muchly appreciated.

2007 Fabia 1 1.4 TDi

1) Cranks fine, just no hint of firing. Tacho does not move when cranking.

2) Diesel going in and out of filter

3) Swapped Crank and Cam sensors (had previously read error codes)

4) Swapped to a re-programmed IMMO OFF ECU but no difference

5) No fault codes stored.

Any help and ideas very much appreciated.

Regards

Fergus

Check fuses in engine bay for blown/looseness and corosion. There are strip fuses in my sons that have failed but the hairline crack is so fine almost impossible to see.

Not sure if there is an ECU relay as well

Alasdair

A couple of ideas:

Does the glow plug light come on with the ignition and then go out before you turn it over?

Is there an immobiliser fitted that may be faulty?

Dave

Thanks gents, I'll have a look. At least the immobiliser light never comes on and I can talk to the ECU.

Glow plug lights as expected.

All lights come on dash as expected.

Tested (all good) the relays behind the fuse box. Changed them anyway.

Fuses are good.

If the injector harness is kaput would that show as an error code ?

If its cranking and no codes and no tacho movement then it may be a bad connection/cable to crank sensor or perhaps either the crank or cam sensor you replaced is faulty. Check wiring for continuity and connection from the crank sensor first as I have read they can fail/wiring probs and not create code.

Alasdair

Its a bit of a long shot but check battery as well. If its low then it might not be cranking fast enough.

Alasdair

Thanks. I'll give it a go. The battery good though and spins the engine like mad.

You say the engine 'spins like mad' - does this seem to be much faster than previously?

Is this is the case, I'd suggest getting a compression test.

Ah no, sorry. Just normal cranking with a healthy battery :)

2.5V at the crank sensor plug and earth is good.

Unplugged the sensor and cranked the engine. But no error codes.

I wonder if the 2.5V is what it should be. I had the same with the original ECU.

I had it in my head that its 5V but may be wrong. It might be a bad connection or damaged wire from sensor or ecu is supplying wrong voltage. I'm sure someone on here will correct me if I'm wrong.

Alasdair

I think there's a later type with a hall effect crank sensor which has 5V supply, but I think this one is probably a variable reluctance type where 2.5V may well be correct.

Next step maybe testing the voltage at the ECU…….oh well. Thanks for all the help gents, appreciated.

3 minutes ago, Jalmassi said:

Next step maybe testing the voltage at the ECU…….oh well. Thanks for all the help gents, appreciated.

Good luck. The fact that you tried a different ecu hopefullty it might be its as simple as a broken/damaged wire/connection or perhaps both sensors are bad. How many wires does your crank sensor have?

Alasdair

It’s got 3 wires.

As far as I know three wires is a hall effect and should be 5v but as previously said I may be wrong.

Alasdair

17 minutes ago, Jalmassi said:

It’s got 3 wires.

I think it's probably two signal wires and one that connects to cable screen/shield.

Knowing the engine code or VIN if unsure, would allow me to confirm.

We've been here recently...

Crankshaft Sensor 2.5V - Skoda Fabia Mk1 (1999-2007) - BRISKODA

That was what started the investigation, now I’m back :)

The VIN is TMBJK

Please don't share your VIN openly.

Either pm @Breezy_Pete or he can pm you.

Thanks, Admin.

No need for VIN.

That previous linked thread established engine code, crank sensor type and wiring info to engine ECU.

Check continuity of the two wires from pins 1 and 2 of crank sensor loom connector back to engine ECU pins shown in that top diagram.

I’ll brave the freezing weather tomorrow and have a look. As of now

Pin 3 ground, Checked

Pin 1 and 2 10Kohms with ECU

Is it not strange no speed sensor error code with the sensor unplugged ?

7 minutes ago, Jalmassi said:

Is it not strange no speed sensor error code with the sensor unplugged ?

Dunno, never tried it on a known working system.

I remember when I changed the crank sensor a few weeks ago the tacho showed some life for a whilst but erratic. Still no firing and then it stopped responding at all. I used an inspection camera when the sensor was out and the reluctor ring I could see looked fine.

I’ll check the wires tomorrow and see if my OBD reader can see RPM when cranking.

Thanks again for all the help.

Did you definitely buy the correct crank and cam sensor replacements?

Cam sensor = 045 957 147B

Crank sensor = 045 957 147C

As far as I can see, for BNM engine in 2007.