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Mr.Jimbo

Member Since: 20 Jun 2024
Location: Rugby UK
Posts: 31

Crankshaft position sensor issues

Hi all, got an intermittent (it’s happened twice now in about 7-8 months) where I’ll park the car up driving normally, but come back to it (first instance around an hour, today only 10-15 mins) and the car will fire very briefly, but then just crank without starting.

In both cases I’ve wriggled the CPS sensor wiring/connector and the car then works as normal. After the first time I then took the connector off and cleaned the sensor and wiring/pins and it’s been fine since.

My question though is: should the CPS losing connection/failing actually stop the engine, or is it only used for reference at startup? I understood the ECU needs the CPS signal to be valid at all times, however my car’s behaviour suggests otherwise (or I’ve just been bloody lucky I’ve been parked both times)

On a side note, it blew the filling station attendants mind when I was able to move the car on the starter in 1st gear without it running!

Appreciate any thoughts on this issue. I’m tempted to replace the sensor now or at the least get an oscilloscope to look at the output (will double check the wiring again)

31st Jul 2025 9:29pm

landy andy

Member Since: 15 Feb 2009
Location: Ware, Herts
Posts: 6006

2006 Defender 110 Td5 USW Zermatt Silver

You sure it’s not the immobiliser kicking in?

Your first sentence sounds like it.

How old battery in fob?

31st Jul 2025 9:38pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17971

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

The crankshaft position sensor is needed for the engine to run. The camshaft position sensor is only needed for the engine to start.

31st Jul 2025 10:49pm

Mr.Jimbo

Member Since: 20 Jun 2024
Location: Rugby UK
Posts: 31

Fairly sure it’s not immobiliser - as I’ve had the same but get a red EML with a lightning bolt before which a quick lock/unlock sorts it (tried that several times but no joy) Occurrence 1 was a lock/unlock prior to issue, occurrence 2 today it remained unlocked as I was just filling up.

I did wonder if it might be something like cam sensor not achieving sync, but strange that it fires up right after I mess with the crankshaft sensor.

Edit I should say, on the two times it does it I have no dash lights out of the ordinary, just the oil pressure which goes out with a bit of cranking and the charge light. No indication at all from the car that it shouldn’t start. It’s also a 2003 15p 110

31st Jul 2025 11:39pm

adseybear

Member Since: 08 Oct 2009
Location: Vancouver, Canada
Posts: 266

this seems to be showing as a common problem now at this age with the Td5s.

have you seen there are some kits now available that should fix/prevent?

https://www.empiretuning.co.uk/product/td5...y-harness/ 2003 Defender 90 Td5 CSW Belize Green - "Betty"
1958 Series IIA 109 Station Wagon - "Randolph" - Awaiting Restoration
2019 Jeep Wrangler JL Rubicon - SOLD
2006 Volvo V70 D5 - Ocean Race Edition, SOLD
2003 VW Passat Estate 1.9TDI - SOLD
2008 BMW 320D M Sport Estate - SOLD
2001 Defender 90 Td5 Hard Top - SOLD

19th Sep 2025 4:02pm

Mr.Jimbo

Member Since: 20 Jun 2024
Location: Rugby UK
Posts: 31

I hadn’t, so thanks for that. I had wondered about tracing the wiring back for any damage or chafing - for that price I’m tempted to just replace without bothering.

Touch wood, the car has bee fine since!

19th Sep 2025 8:36pm

MadTom

Member Since: 10 Sep 2013
Location: Olomouc
Posts: 687

Cable to CPS is just a twisted pair with shield
Shield is connected only one side - to ECU. When I was.moving ECU in Disco2 from engine compartment into the cabin, I have simply made this wire. And it work for more than 10 years.
If youe car is suaceptible to manual wigling, look into the connector on the female pins. The often went loose over time. Wit help of a needle, the can be tighten a bit back. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo

19th Sep 2025 10:05pm

rustandoil

Member Since: 08 Sep 2012
Location: Cotswolds
Posts: 886

2005 Defender 110 Td5 XS DCPU Bonatti Grey

It's clear you've pin pointed your fault 👍🏼

Just got to decide the fix personally I would get the Empire overlay loom and a new sensor....

TD5 cam sensor?... Where's that?

20th Sep 2025 7:38am

DefenderCan

Member Since: 25 Nov 2023
Location: Canada
Posts: 33

TD5 does not have a camshaft sensor.

20th Sep 2025 8:00am

rustandoil

Member Since: 08 Sep 2012
Location: Cotswolds
Posts: 886

@DefenderCan....exactly 👍🏼

20th Sep 2025 10:08pm

Procta

Member Since: 04 Dec 2016
Location: Sunderland
Posts: 5361

These Crank sensors look very much like the Rover K series ones, Defender TD5 90 ---/--- Peugeot 306 HDI hatch back

In the words of my Good Friend, Gary Forrest 1980 -2025
" we will work something out"

21st Sep 2025 12:29am

Mr.Jimbo

Member Since: 20 Jun 2024
Location: Rugby UK
Posts: 31

Thanks all for the input - I think I'll take a close look at the wiring and for that price, probably just replace.

Always amazes me how long an intermittent connection can be OK for, and then suddenly not!

22nd Sep 2025 12:40pm

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