Car won't start after battery out for extended time

Hi all, so after getting a coolant leak that got worse and worse (thermostat housing cracked), I finally found the time to do the work myself. I bought a new thermostat and housing, and the crossover pipe and after having to remove half the engine, I finally got the new parts fitted and added the coolant, ready to start it up and test it out.

But when I try and start the car, absolutely nothing happens, no turn over, no click, and the battery has good voltage.

Now, I've done a search and seen some people reference that if you're going to disconnect the battery for a decent amount of time, that there is some kind of procedure to follow however if that is true, then I didn't do that.

So, the key can lock and unlock the car, and I can turn the accessories on, can use the lights but the windows won't work.

When I turn the key, I can hear the HPFP priming, but when I try turn the key fully to turn it on, nothing happens at all. If I sit in the car with it unlocked, after about a minute, the car will automatically lock, so I think this means it can't detect my key, meaning perhaps the key has lost its sync or registration with the car?

I've seen that there is some kind of BSI Reset procedure, but I can't even do that because it involves putting the drivers window down and it won't do it.

So, having disconnected the battery without following any particular procedure, leaving it off the car for about a month while I worked on the thermostat etc. does this mean now my keys are no longer synced and the reason it won't start is because it cannot detect my key and the immobiliser is staying activated, which is why the car won't even try to turn the engine over?

If all of that is true, and my keys are no longer linked, how am I supposed to re-link them?

I've hears of software called PP2000 which apparently you can used to do all sorts of things when you install it on laptop and connect the the OBD2 port, but I've also heard you need some kind of PIN number that will let you unlock the ECU etc.

Hoping the Peugeot experts will tell me this is an easy fix and nothing to worry about lol

To add, was getting the 'economy mode active' message, but after connecting a power pack so that the voltage was high enough to start, the message disappears so that has nothing to do with the issue.

But, I noticed when turning the key to ACCESSORIES position, after the HPFP primes, the cluster shows an 'M-' symbol, does anyone know what that is?

The BSI reset is nothing more than letting all modules sleep (> 3 minutes) and then disconnecting the battery for several minutes. Easily donebonnet open, wait more than three minutes and then disconnect battery. Do not open or close doors in this time.
There is also a procedure to relink the key (I thought holding the open or close button when in ignition, should be on the forum somewhere). But I think this only relates to remote lock/unlock. Not sure though.
OBD is your best bet. Maybe you disconnected a cable by accident? Also no relais sound when starting?

JvdBosch said:

The BSI reset is nothing more than letting all modules sleep (> 3 minutes) and then disconnecting the battery for several minutes. Easily donebonnet open, wait more than three minutes and then disconnect battery. Do not open or close doors in this time.
There is also a procedure to relink the key (I thought holding the open or close button when in ignition, should be on the forum somewhere). But I think this only relates to remote lock/unlock. Not sure though.
OBD is your best bet. Maybe you disconnected a cable by accident? Also no relais sound when starting?

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No sound at all when turning key to 'ON' position, the car has zero reaction, no sounds, nothing. That's why I think the keys are no longer connected. I can turn the barrel because the physical key is obviously for the car, but the electronics aren't linked so I imagine the immobiliser and car ECU aren't responding.

This is why I think the car automatically locks after about a minute, even when I'm in it with the key, because if the key was detected, then it wouldn't be doing that.

Looks like I'll need to maybe programme the keys again as if they are new keys, and to do that I found some reference to Diagbox software with a USB to OBD2 cable called 'Lexia3', which I can see there are plenty on Aliexpress but the costs vary a bit so I'll have to research a bit more and find out which one is good.

Also, to programme the keys you need a PIN number, which I don't have, so it looks like I'll have to contact Peugeot directly and get them to tell me what the code is after I prove I own the car I assume. That's going to take some time, because I'm in Australia and I bet the service techs here will have to request the PIN code from Peugeot in Europe who should have that information.

Worse case scenario the immobiliser could be the culprit & you will need to reprogramme the keys as the car might have lost the signals from the keys ?
Silly suggestion lock the car then try rocking it to see if the Alarm works ?

Pedro said:

Worse case scenario the immobiliser could be the culprit & you will need to reprogramme the keys as the car might have lost the signals from the keys ?
Silly suggestion lock teh car then try rocking it to see if the Alarm works ?

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Actually, I can lock and unlock it with the buttons on the key. When I sit in the car, after about a minute it automatically locks and then I can see the lock button and parking sensor button on the dash light up constantly one after the other, as if to indicate the alarm is on.

Here's the thing though, if the key had lost its connection to the car, wouldn't that mean the lock/unlock buttons on the key wouldn't work?

So, maybe the keys are still in fact linked, but maybe when I plugged everything back in after having a lot off the engine, maybe I missed something or plugged something into the wrong plug? Just having a look over the engine, I can't see anything obvious but still, maybe one of the plugs I can see.

But if its a plug that is in the wrong socket, or if I haven't plugged something back in, wouldn't the system show an error that is more specific?

Just floating any ideas at this point.

Just a thought, There are some fuses under the bonnet, including some that the handbook states "must be done by a PEUGEOT dealer or a qualified workshop." Worth checking them ?

chrismac said:

Just a thought, There are some fuses under the bonnet, including some that the handbook states "must be done by a PEUGEOT dealer or a qualified workshop." Worth checking them ?
View attachment 15698

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Yeah thanks for that suggestion, had a check it all ok.

But I happened to have a new BPGA module sitting around so had a hunch and after disconnecting the battery, swapping over the BPGA module, then reconnecting and now it starts!

Funny thing is, the BPGA module that I had in there is fairly new, not even a year old, as the original factory one was playing up.

So I don't know what I did to affect the BPGA module but the new one at least let me start the car, and of course it wouldn't be Peugeot if you didn't solve one problem and have to deal with another....now the car is alerting that there is a problem with the brakes and a problem with the engine. Obviously there is nothing actually wrong with either of them, its probably a symptom of changing over the BPGA module and I'm hoping after driving it around for awhile, the codes will clear and then it won't be in limp mode anymore. Because even though I can drive it now and everything is fine, the new thermostat works, no coolant leaks etc. its in limp mode so very gutless.

So with error codes, will those automatically clear once you drive it around for awhile or do those kind of error codes need to be cleared by a service tech with the fancy equipment so I can get it out of limp mode?

A BSI reset might also reset fault codes. But there are cheap OBD modules and free phone apps to reset codes.

RCZ-mad said:

Actually, I can lock and unlock it with the buttons on the key. When I sit in the car, after about a minute it automatically locks and then I can see the lock button and parking sensor button on the dash light up constantly one after the other, as if to indicate the alarm is on.

Here's the thing though, if the key had lost its connection to the car, wouldn't that mean the lock/unlock buttons on the key wouldn't work?

So, maybe the keys are still in fact linked, but maybe when I plugged everything back in after having a lot off the engine, maybe I missed something or plugged something into the wrong plug? Just having a look over the engine, I can't see anything obvious but still, maybe one of the plugs I can see.

But if its a plug that is in the wrong socket, or if I haven't plugged something back in, wouldn't the system show an error that is more specific?

Just floating any ideas at this point.

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Pretty much impossible to put wrong plug in different connector I would scan the car & be prepared for numerous fault codes to flash up as in a Flat battery issue losing power to the ECU etc will be problematic as for the key once you insert it in the ignition the car is reading all that info in milliseconds thus the commands to initialise all the cars systems to power up for staring will become active if you have a fault from the key to the ECU you could have Canbus issues which means loss to some or all of the important function systems hence car stay inactive even though it has a full battery ?
Is the Alarm working as in shake the car to see if the immobiliser is active ?

Pedro said:

Pretty much impossible to put wrong plug in different connector I would scan the car & be prepared for numerous fault codes to flash up as in a Flat battery issue losing power to the ECU etc will be problematic as for the key once you insert it in the ignition the car is reading all that info in milliseconds thus the commands to initialise all the cars systems to power up for staring will become active if you have a fault from the key to the ECU you could have Canbus issues which means loss to some or all of the important function systems hence car stay inactive even though it has a full battery ?
Is the Alarm working as in shake the car to see if the immobiliser is active ?

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I started it up and ignored the messages about faulty brakes and engine, since I could feel the brakes working and the engine was running fine. Since I fitted a new thermostat and crossover pipe, I had it idling so I could watch the coolant temp rise, and make sure that the waterpump kicked in, and it did, and temp remained constant.

I went for a 10minute drive and all seemed ok with the exception of one thing...its definitely in limp mode, because its lacks power badly. There is nothing on the cluster to indicate any limp mode, but the performance is trash so I can tell.

I'm hoping that it will right itself after a drive or two. If it doesn't, then either I've forgotten to plug something back in lol.

One last thing, after I went for that drive and came back to the garage, I popped the bonnet and could smell a light burning plastic smell, its unmistakeable. Now, when I had the intake manifold off, I had to move wiring around at the back of the engine as I was working, I hope that some of the wiring conduit isn't out of place and perhaps leaning against the engine and melting, otherwise I'm going to be in real trouble if it melts all the way through. I'm hoping the plastic smell is just the thermostat getting hot, as its new and sometimes plastic parts give off an odour.

Ok so I've taken it for a decent 1 hour drive, it still complaining that there is an engine fault, so its in limp mode. I have a basic OBD2 scanner but it says no error codes, I need something more capable to use. Any ideas where to get that Lexia3 cable and Diagbox software from?

Sorry no I use Peugeot Planet or one of 3 other scanners mainly the Autel for other cars

Before spending lots of cash and time consider booking into a garage for a full diagnostic scan. Not necessarily a Peugeot dealer, My local garage had a suitable device for identifying which ABS sensor was damaged. An OBD2 couldn't do that.

Bite the bullet (or the Australian equivalent). Its going to save time and money in the long run.

I have a PP2000 from my 406 Coupe days, but for the life of me I can't get it talking to my RCZ.

If of use, and i am not advertising for them but I have a Launch reader and with an annual subscription for full Peugeot I can see and read everything I have tried to so far including all wheel speed sensor. It allows bi directional with a lot of stuff too, again everything I have tried to so far. There may be stuff it can’t do, but to date that must be stuff I havent tried.

The scanner will only have access to systems in its own programmes & on most modern cars the ECU BSI can have manufacturers locks which may mean you have to buy the dealer supplied downloads if they will allow that to happen as you may need to be a bona fide Garage There was a guy on ebay who sold the Planet Diagbox downloads I had one off him & it works OK

Bit late to the party here but it sounds to me like the car immobiliser has kicked in when the battery died (as it would if a thief tried to disconnect the battery to gain access to the car to steal it).

I had the same issue with a previous car of mine and after much swearing and head-scratching finally managed to cure it with one person in the car turning the ignition at same time as somebody else with the bonnet up reconnecting the battery leads in the engine bay.

Not strictly the safest method but fixed the problem and it never happened again after. So be careful if you try it and good luck!

Well I've driven it for a few days and its completely normal in all aspects except, its in limp mode. The error message on the cluster simply says 'Engine fault'.

Since the car performs fine, I wonder if the ECU logged some errors when I had the initial issues connecting everything back up, and now perhaps I have to get the errors cleared by an actual Peugeot workshop?

I know some errors you get will clear by themselves when the condition that caused the error is resolved, but are there some errors that stay until they get cleared?

At this stage, I'm going to take it into a garage so they can use the proper tools to tell me what the issue is.

If you clear the codes always check at least twice as in Ignition off then on again to make sure they are not still live as clearing DTCs does not guarantee the faults showing actually are eradicated ?

Pedro said:

If you clear the codes always check at least twice as in Ignition off then on again to make sure they are not still live as clearing DTCs does not guarantee the faults showing actually are eradicated ?

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Yeah I know but the I'm certain most of the codes were generated from the electrical gremlins, so the idea is to clear the codes, drive around and see what pops up again, if at all.

So I took it to an independant garage and they hooked it up to their Autel scantool...about 10 error codes listed (like ABS, coolant etc.) so he cleared all of them for me except....there is one code left that he isn't able to clear, and we have no idea why we are prevented from clearing it.

The code is F40A, referencing something about oil gauge sensor. I've done a quick google search and sure enough, plenty of people have had this exact error come up but I haven't been able to find a solid answer as to how to clear it, yet.

Obviously, what people say on forums should be taken with caution, but I've seen someone mention that if the car sees a 40 degree difference in temp between the coolant and the oil that it can trigger this, so if the oil temp sensor is dodgy?

Thing is, I never touched anything to do with the oil system at all. The only thing I could see potentially affecting it is that I had to move the wiring loom out of the way so I could remove the thermostat, and this car being 15 years old, perhaps that movement has broken a wire or at affected its connection, and now the system can't read the oil sensor?

I don't know where that sensor is actually located yet, so I'm going to find that out and then have a look if its plugged in and the connector is in good nick.

If the sensor or its wiring is located at the side of the engine that is at the back, then its possible I could have damaged the wiring when I was struggling to get the coolant crossover pipe in place, but I'll have to do a little digging to find out where it is exactly. Unless any of the resident experts here happen to know where it is? Lol