ok I have been reading a few articles on resetting the ecu of a car and how it may help various things like mpg and stuff like that.

I have decided to give this a go as I want to see for myself if it makes any differences. To be clear my car is fully serviced and running 100% only iggle I have is a slight lack of pull/throttle feeling when I'm pulling on hills ect. So I decided to try a reset first just to see.

The aim of this test is basically to see if any difference can be noticed in any way or form.

I can not find a guide of sorts but I plan to do the following:

1)Disconnect Battery Negative terminal.

2) Let car sit for 1hour to discharge all.

3) reconnect Terminals

4) Start car allow to idle for 10 - 15 min without touching accelerator

5) Take for a drive and drive the way I normally do

6) Continue my normal driving style throughout the week/Month and see if there is any kind of difference at all.

any Input here would be greatly welcomed and encase any one suggests yes I do have the radio code so don't worry lol!

I Read that James (Jeebowhite) has reset his mondeo and I think his cmax and he noticed an improvement in the mpg and I have also read that some people suggest a reset after each service or change of a senor, air intake as in a sense this changes the environment of the engine (example new or updated air filter will allow more or clean air through so ecu can adjust or alter other things to suit this change in the engines environment ect)

Now to be clear I'm not saying this works or does not work I'm just restating what I have read and heard from others hence the reason I would like to try this out for myself.

so any advice or input is greatly welcomed here and hopefully by the end we should all have a good insight in how the ecu works and if a reset actually does or may help.

Thanks for reading.

:)

Well, what harm can be done!

Mines a little low on where id like its MPG to be, probably because I thrash it every now and then to "make sure its ok" :)

Be interesting to see if you could actually map this out using forscan on a laptop and a EML327, getting two idle data sets would be easy, getting two driven tests might be a bit harder. Might help with spotting differences rather then "feeling" them though

Just disconnecting the battery doesn't reset all the data the ECU holds. To do a full reset, disconnect the battery negative, run a jump lead from disconnected and isolated negative plug (not battery terminal) to positive terninal/wiring). Apparently doing that for a few minutes drains any capacitors in the loop, causing everything to reset, which doesn't necessarily happen just disconnecting the battery. Stuff like pedal position sensors and automatic gearbox shift points all get reset using this method.

Another way may be to disconnect the battery while the ignition is still on - that way the ecu drains any capacitors itself before it fully powers down.

On the ST there is a specific fuse you can pull, leave out for 30mins or so then replace which supposedly resets the ECU. However in the past when I reloaded a bluefin map onto one of my cars, the first time I put my foot down it blew the clutch away. No long lasting damage done but it did stink for a bit.

Also know someone who monitored a ton of running data after resetting ECU (ST again) and the car wasn't fuelling very well etc for quite a while till it settled down. May have felt sharper to drive but not actually the case.

Disconnecting a battery on a running engine can/will do a LOT of damage to relays and ECU's. DONT ever do it. The battery is the largest smoothing capacitor on the car

That's why I said ignition on and not engine running :)

Still not a good idea, you don't pull the plug on your computer while its running, you shut it down first, Any damage will not be warranty covered as the user manual explicitly says never to do that

These cars are not like the old ones, where ignition on just was a 12v feed, nowadays the fuel pump runs to prime the rail, lots of solenoids are activated, cpu's powered up and running code in the background, Physical systems like EGR, wastegate, shutters etc are cycled and tested for operation etc Plenty of things going on that a dead kill in the middle may not be recoverable

Also with the puters on board now, even resetting the ECU is not like the old cars where it forced a relearn cycle on the idle timing and fueling over the next few run cycles. Yes it will drop some tables to be relearnt but many of the new tables average over large numbers of run cycles (say 20) so optimum run condition may not bee seen again for some time. That's why I cringe every time I see someone say unplug it to reset the puter. Its just not that simple anymore

Ok little update here. I did this yesterday and drove 6-7 journeys ranging from 5mile to 35 mile a journey being from car start to car stop lol! and I don't know what to say really.

I did notice a slight difference on each journey kind of like the car adjusting or something but on each journey I tried do the same thing in regards to my driving. I changed gear around 2250 rpm and used the throttle as I would under normal driving. also when coming to a stop I gently slowed the car down using the brakes and gears where as before I would of been a bit more of a "just stop" guy lol!.

Now this morning I have noticed that the car does feels a little more smoother and pulls more smooth on inclines but I don't know if I can truthfully say it has made a major difference but I would go as far as saying it has made some maybe although I do believe that I need to do some more journeys to see how it maps out. I think that through a few more journeys of my normal driving the car may settle from the reset and I may or may not noticed anything but I guess time will tell.

Will a reset do anything towards a DPF clean???

53 minutes ago, Davidhayne said:

Will a reset do anything towards a DPF clean???

No.

Hi sonic113, did you manage to reset the ECU of your Ford Focus by following the steps above? If so, did it help with reducing lack of pull/throttling up the hills that you have mentioned? Thanks

My 2014 ford focus zetec keeps going in to limpmode no warning lights come on the dashboard or no problems shows up when my mechanic puts the dynastic computer in he think its something to do with uce needs flashback or resetting anyone had problems like this before? 

Hi my son has a Ford ka, he wanted his car to pop and bang, some lad came down and said he could do it, but now the car won't start, he has told us that a guy has bench it, but it's still not working any ideas 

It has probably popped or gone bang. 

My Ford focus is getting10 mpg ,2000cc fual injected 2007 what's up ! How do I improve the mpg 

On 9/24/2021 at 2:37 PM, Pamela follows said:

Hi my son has a Ford ka, he wanted his car to pop and bang, some lad came down and said he could do it, but now the car won't start, he has told us that a guy has bench it, but it's still not working any ideas 

Reflash with the OEM map

15 hours ago, Browning said:

My Ford focus is getting10 mpg ,2000cc fual injected 2007 what's up ! How do I improve the mpg 

10 MPG?? I would definitely stop driving with the handbrake on! 🤣

Don’t know if anyone can help. I’m getting p2237p on my st mk3.5 diesel. Changed the sensor today and still getting the code. Messed around with the plug earlier and left it and code was gone but went for a long drive and stopped and ignition on and same code was back. Any ideas 

The P2237 code is a generic OBD-II code that indicates an issue with the oxygen (O2) sensor heater circuit in Bank 1 Sensor 1 of a vehicle.

If you want to get the full Ford specific DTC's then you will need to use 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

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

 

Search Tag:   FORScan123

 

Right ok, it does bring the mil on. Getting voltage to the plug that plugs into the sensor. 
 

looked on Google and it says sensor or wiring, failing that could be exhaust leak or pcm. I’m at a complete loss 

@unofix forscan is showing this mate 

If you can shed any light would be much appreciated. Changed sensor for genuine Ford and today changed plug that goes to the sensor plug to no avail 

3 hours ago, James pritchard said:

Changed sensor for genuine Ford and today changed plug that goes to the sensor plug to no avail 

That's a problem for sure.

I'm out of ideas just now, perhaps @TomsFocus might be able to think of something?

14 hours ago, James pritchard said:

If you can shed any light would be much appreciated. Changed sensor for genuine Ford and today changed plug that goes to the sensor plug to no avail 

 

11 hours ago, unofix said:

That's a problem for sure.

I'm out of ideas just now, perhaps @TomsFocus might be able to think of something?

Nothing cheap unfortunately.

This does seem to be an error with the sensor return readings for the PCM, rather than the heater circuit.

Next step should be checking the wiring from the sensor plug to the PCM plug, but I don't know how easy it is to access the PCM on a Mk3.5 and is probably best left to an auto-electrician.  If the wiring checks out ok, you could have the PCM tested while there is access to it, but that probably won't be done for free.

On the petrol's around the same age, there is some procedure that Ford often have to carry out after a lambda change to prevent the fault coming back, but unfortunately we only get second hand information from the customer, so I'm still not sure exactly what's being done and whether Forscan can do it.  For a free check, it would be worth checking under service procedures to see whether there's any sort of reset for lambda learned values, or words to that effect.

@TomsFocus Much appreciated for the reply buddy. I’m going to get the wired checked all the way back to the pcm. I’m just going out to it now to put multimeter on it (plug) while engine running so I’ll take photos of the readings as I can’t load videos and hopefully you’ll spot the issue just from them 🤞🏻