Hello,

I hope that someone can help and offer advice with this issue.

Ford Focus 2003 will not start/ turn over. Starter motor tested OK.

Correct key - i.e. started car previously -  central locking still works both with key and with remote.

Scanned with results as follows;-

Make: FORD

Model: Focus 1.6L 

Year: 2003  

PCM Powertrain Control Module

DTC                                                         Description 

 

P1000                                                      On-Board Diagnostic (OBD) Systems Readiness

                                                                Test Not Complete

B1601                                                      PATS(Passive Anti Theft System) received incorrect 

                                                                key-code from ignition transponder.

B1342                                                      ECU(Electronic control unit) internal fault 

Markings on Central Locking Module/ GEM 

                                 Siemens  1S7T-15K600-KE

Markings on  ECU

                               Visteon LP4-335 1-00 0287  2ANA  1M5F-12A650-BE

                              0308 009 OSRAM SYLVANIA  E9AF 14A624 AA  FOAF-14A459-AA 

Could this be a problem with the keys (both?),  the immobiliser transponder  (located around the lock barrel), the GEM or ECU (or both the latter)?

Any expertise, opinion and suggested course of action would be gratefully received.

Further details;-

On this vehicle there is no immo /Key symbol  on the dash display, there is however an immo flashing LED to indicate alarm/immo status.

Please see attached image in doc;-

Image 1 - shows dash display with key in II position.

Image 2 -  shows LED above clock

               => LED - slow flashing - no key - normal

               => LED  - rapid flashing - key in position II - LED does not go out.

It has been suggested that this infers that the key-PATS circuit/function is not working correctly (as perhaps per code B1601) - Is this controlling circuit contained in the ECU or elsewhere (e.g. dash display?)  i.e. Is this because the ECU is suspect /"faulty" (code B1342) or could this be erroneously showing as a fault in the ECU, because the fault is elsewhere? (e.g.  the immobiliser transponder  (located around the lock barrel))

If the ECU is faulty could this be the only reason why the keys are not being recognised ? - and if so would testing of the ECU show this (and a repair/ re programming cure this and the keys would be accepted? 

The battery was allowed to discharge - then I took the battery off the car, recharged it and then put it back in the car. - could this cause the issue.

Do you think the issue with PATS (keys not recognised) could be being reported back as an "Internal fault" with the ECU when in reality the ECU is OK ?

And if so, if the chips in the keys are re programmed, the car may then start?

If however there is an internal fault in the ECU, is that something that  could be  repaired ... or cloned?

And if a repair/ direct replacement is not possible, is it feasible to replace the Visteon unit with another branded one, and what would this involve to get it to work correctly?

Update

In the interim I found a local guy who checked the car out with his software (Forscan), and found the same fault codes as we did. He told me there were 8 keys registered (which seems very unlikely the previous had 8 keys! –I have 2 ) and that he couldn't re-programme any keys (as he thought he would be able to do).

What can you draw from the above results ?  

Therefore I would be grateful if you could please advise of the most likely cause of this issue and suggest a successful remedy/ diagnostic route.

Thanking you in advance for your time and consideration, I look forward to any replies.

Ford Focus Images 12-8-25 .pdf

The problem is without any doubt the immobiliser.

The system is not recognising the keys. So firstly to clear up any misunderstandings, it is the car that gets programmed to accept the code from the passive chip in the key, not the key that get programmed.

You really should be using FORScan to get the full Ford specific DTC's which may give you a bit more information. In any case if the car's memory has forgotten the code of the keys then you will need FORScan in order to reprogramme the car.

Just as a side note: The locking/unlocking using the keyfob is separate to the PATS immobiliser and is programmed separately as the two systems have nothing to do with each other.

One known issue on models of your cars age is faulty soldering on the instrument cluster. This will cause a fault with the PATS and prevent starting. A general test is to give the dashboard a good couple of 'thumps' with your hand just above the instrument cluster. This will often give a very short term fix and allow the car to start.

I've known Fiestas of the 2003/2004 age to completely forget the keyfobs after an extended period with a flat battery, so it is possible this might also happen with the Focus of a similar age.

FORScan:

On 4/7/2024 at 8:59 PM, unofix said:

FORScan (for use with Windows Laptop) : https://forscan.org/download.html

It's what many Ford owners use including some Ford technicians.

• vLinker FS, cable for laptop: https://www.amazon.co.uk/Vgate-vLinker-Adapter-FORScan-MS-CAN/dp/B0952P4MLP

OR

• OBDLINK EX, cable for laptop: https://www.amazon.co.uk/OBDLINK-EX-FORScan-OBD-Adapter/dp/B081VQVD3F/ref=sr_1_5

For diagnostic use only:

• vLinker FD, for android phone: https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H82WC8L
• vLinker FD+, for iPhone: https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H8JHWP2

 

On 8/12/2025 at 5:58 PM, unofix said:

The problem is without any doubt the immobiliser.

The system is not recognising the keys. So firstly to clear up any misunderstandings, it is the car that gets programmed to accept the code from the passive chip in the key, not the key that get programmed.

You really should be using FORScan to get the full Ford specific DTC's which may give you a bit more information. In any case if the car's memory has forgotten the code of the keys then you will need FORScan in order to reprogramme the car.

Just as a side note: The locking/unlocking using the keyfob is separate to the PATS immobiliser and is programmed separately as the two systems have nothing to do with each other.

One known issue on models of your cars age is faulty soldering on the instrument cluster. This will cause a fault with the PATS and prevent starting. A general test is to give the dashboard a good couple of 'thumps' with your hand just above the instrument cluster. This will often give a very short term fix and allow the car to start.

I've known Fiestas of the 2003/2004 age to completely forget the keyfobs after an extended period with a flat battery, so it is possible this might also happen with the Focus of a similar age.

FORScan:

 

Hello unofix,

Thank yo so much for your very helpful reply,

I now have Forscan and a vLinker FS, cable for laptop and have got the same codes detected as in my original message - namely;-

DTC                                                         Description 

 

P1000                                                      On-Board Diagnostic (OBD) Systems Readiness

                                                                Test Not Complete

B1601                                                      PATS(Passive Anti Theft System) received incorrect 

                                                                key-code from ignition transponder.

B1342                                                      ECU(Electronic control unit) internal fault 

 

I am not sure if these are or are not "full Ford specific DTC's " to which you refer ? Please clarify / explain how to obtain the latter if appropriate.

When you say immobiliser, where is this? Is it separate or within the ECU or BCM?

I tried the thump x2 on the dashboard top to no avail ! Shame ! => looked at soldering on dash display PCB - looks ok no obvious cracked solder joints but will recheck !

Re  "I've known Fiestas of the 2003/2004 age to completely forget the keyfobs after an extended period with a flat battery, so it is possible this might also happen with the Focus of a similar age" - will the keyfobs be "remembered" when re charge battery ? What to do if not the case ? How to reprogramme the "whole" car?

Is the fault shown in the ECU "real" or caused by the immobiliser or vice versa!

What would do next? 🤔🙃😩

Sorry for all the questions but any help would be much appreciated!

Thanking you very much in advance for your information & knowledge, I look forward to you reply.

 

Hi Clivey .

Take a screen shot of FORScan with the DTC's so we can check if there is any hidden info that might be of help.

You need the battery to be in 'Tip Top' fully charged condition before trying to diagnose anything further. Then use FORScan and clear all DTC's and see what codes come back.

Are your keys the original genuine Ford ones ? How many keys have you got ?

Please do not attempt to resolder the instrument cluster yourself. I'd recommend getting it serviced / resoldered by @rd457 and then at least you can rule that out as a potential problem.

Hello again,

I have used Forscan & took the following screenshots (attached) - I hope they reveal more info for you!

I have 2 keys - both original Ford keys that came with car and worked /started car etc  OK for weeks prior to present issue arising (i.e. non-star scenario).

I fully charged the battery and load tested it prior to Forscan.

I have dismantled IC and examined soldering on PC board /around socket (under magnification) - all looks OK, no obvious cracks. Self test of IC - all good.

I hope the above and attached give you more clues to go on !

 

 

 

Looking at the DTC's for the keys, I suspect that you have been repeatedly trying to programme the car to recognise the keys to the point it now thinks there are 8 keys. This is potentially a problem as the same key will have been programmed in multiple times.

You need to first follow 'to the letter' the exact instructions of how to delete/clear all keys from the vehicles memory. FORScan have instructions on how to do this. Provided that the two keys you have are both genuine original Ford keys, and not aftermarket keys, it will be possible to programme the car to recognise each of them. Please not all keys must be deleted first, and then both keys programmed in, one immediately after the other.

What "outcode" are you using ?

The Focus MK1/MK1.5 does not use the INCODE/OUTCODE system (Coded PATS).

It uses the older Timed PATS system that uses a time delay during the PATS programming procedure.


Also note that on the Focus MK1/MK1.5 the instrument cluster is not part of the PATS immobilizer system. The car will start/run even without the instrument cluster connected.

On the Focus MK1/MK1.5 the PATS system is fully integrated into the PCM. No other modules are involved.

5 minutes ago, JW1982 said:

The Focus MK1/MK1.5 does not use the INCODE/OUTCODE system (Coded PATS).

That was also my original thought until I saw the DTC's generated by FORScan saying the OP had entered the wrong incode, hence my question asking about what outcode was he using.

I suspect that Forscan is causing these DTC codes. Forscan has very limited support for the Focus MK1/MK1.5.

I have seen before that Forscan incorrectly used the Coded PATS procedure on a Timed PATS based vehicle which resulted in the vehicle becoming immobilized.


 

 

 

Thank you for your very helpful replies!

UPDATE 01

Have applied Forscan with following results (screenshots):-
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I hope someone can look at the above and offer advice as to where to go next !

Cleared codes but they came back .

 

UPDATE 02

I have tried to re program the 2 keys (originals from car manufacture which worked up to issues occurring) using 12 min timed access - gets to 73% then security access denied! (see below)
Interestingly shows 8 keys stored (as per initial scan) and was never the case!) Couldn't erase any stored keys.
 

 

 

 

 

Thanks for any help and guidance offered - much appreciated!

16 minutes ago, MrCee04 said:

Interestingly shows 8 keys stored

8 is the maximum number of keys that can be stored (even if there were never 8). Until a way is found to delete all keys from the vehicles memory you won't be able to add anymore.

This is the sort of problem that I've seen happen when one or even both of the keys are clones of an original. That said it should not prevent all keys from being erased from memory. The FORScan technical help forum is offline at the moment, something to do with Russia having a bit of a falling out with their neighbours.

Hi, can I ask if you have made any progress. I have the exact same problem. My keyman says the main ECU is at fault. So am looking for a repair or used one. 

5 hours ago, FordFocusPete said:

I have the exact same problem.

You could have the same fault, or then again you might have a totally different fault.

What are the Ford specific DTC's read using FORScan ?

 

Sorry for delay. Quoted by locksmith,  fault code B1342 which relates to ecu not working. Also found 8 keys stored in system. This is probably me trying the reset my existing keys using internet info. Have this issue. I cannot start my engine (will not crank). Main Battery went flat when in storage at home (dropped to 4.6volts), fitted new car battery, starter motor, crank sensor and clutch pedal switch. Tested starter relay/30amp fuse in engine bay. Engine still will not crank. All dash lights are on. Noticed PATS light continues to flash when I turn the key. Central locking works. Could it be a PATS issue? ..2004 Mk1 1.6 6000miles. Some more research indicates if a Ford Focus or Mondeo has been stood for a long time and the car battery has gone flat, the car forgets the keys". a possibility? ps believe PATs light flashes 1:5 (15)...Assume Fords will not look at this due to its age. Planning to send off my ECU to ACTronics for testing/ repair.

14 minutes ago, FordFocusPete said:

Central locking works. Could it be a PATS issue?

The central locking system with remote operation is a totally separate thing to the PATS system. They operate and are programmed independently.

You need a licensed version of FORScan and a vLinker cable. Then use it to delete all keys (however many that is). You will never be able to programme in a working key while the car's PATS system is full.