Big mistake reversed battery

I know it should be beyond any idiot but I managed to fit a new battery in reverse, realised mistake and re fitted now the issues car won't turn over, multiple failure warning light and oil level failure light now showing , radio also not working. Any ideas what I have destroyed in my error I'm a guessing the ecu but hoping not the case. I am in south east London if any one has any recommendation re where I should go Windows lights and wipers all seem to be working check radio fuse and ok but I believe there is another fuse on the reverse

I did it on my 914 last weekend, I have fried the alternator for sure, dont know what else yet On a 1975 car I dont have a lot of electronics in comparison to you

Did it my Alfa 156 15 years ago when jump starting it. Needed a new ecu.

Fried ecu would be my fear

I was lucky. Mine was a company car and I denied all knowledge of how it had happened. I think a new ecu was around £800 at the time. I guess you'd get one for a 996 much cheaper 2nd hand.

Needed a new ECU in my boxster a few months ago. In order for it to be plug and play you'll need to buy the ECU, immobiliser and key as a set. Swap them all out and you're good to go. Think I paid about £300 off eBay from memory. :thumb:

First off can i just say this is actually an easy mistake to make .. both leads are black and a LHD and the battery is reversed .. the instructions in the old original manual actually had the LHD instructions ! What's damaged though .. i'm afraid it varies .. there is no set combination of control units .. alarm module is usually the first .. possibly the alternator .. radio / pcm and usually just a fuse blows . Dme is possible but i've seen these without a Dme failure . First point of call .. a fault code read out to see which control units are communicating and which are not .. then its a case of fuse checking .. you can do this yourself if you wish .. just pull and look at the fuses .. that will give you an idea at least. if you have any type of code reader i can help diy to a degree . I'm sorry to say i've fixed one or two of these over the years and cost wise .. i would Hazard a guess at £2K .. but its unpredictable i'm afraid so that's a guess on my part . If it was a 997 then far higher .. last one i repaired was 6 control units fried and something like £4K . Any Porsche garage will be able to fix your car .. if you wish i can give you details of mine but to be honest i don't consider myself to be any different from any other garage and as we are approx 40 miles from you then a local garage will do just fine .. needs to be a Porsche Indy though . EDIT .. Second hand ECU and you need the alarm control unit and a key fob along with the donner car details .. chassis number etc .. ebay sometimes have these listed as a kit ... no chassis number of the donner kit and you can never code a new key fob on .

I did exactly the same a few years back when fitting a new battery to my 996 in a poorly lit garage. It's easily done! I fried the alternator and the awful Xtrons head unit my car came fitted with. Alternator cost £20.00 for a repair at a local electrical specialist and the head unit went where it belonged... in the wheelie bin. I've since wrapped the positive lead in red electrical tape to prevent future errors. I hope you get off as lightly as I did! 😊

Priority job tomorrow find some 'red tape'!

Yup, easily done by anyone. I hope it's a relatively simple solution for you.

Thanks everyone for the response don't feel such a dumb ass now and will be using the red tape idea in the future. DeMort thanks for the more technical response I have contacted my local indi (Beckenham) to see what they think, As you say the south coast is a bit of a slap otherwise you would be where I go, I may come back to you in the future though as anyone who can be so generous with help and advice deserves my business.

Definitely Doing this because there's no way I'll remember reading this until this happens to me !

I have a code reader and live close to you in Hayes if You want to check what is going on?

I could never understand why the OEM battery people don't make life easy by using a round pole for positive and a square pole for negative that way you would have to be really forceful to wire it up wrong

Anti Corrosion Washers I keep these in stock and when I buy a new battery, fit them. Along with sleeving the +ve cable ( or indeed red tape! ) then you have to be particularly distracted to fit it incorrectly! Totally agree that posts should be round and square and why do manufacturers put a tiny moulded + or _ on the case? Make them big and preferably coloured so we can see them https://www.ebay.co.uk/itm/Car-Auto...819935?hash=item1ce0b199df:g:Fp4AAOSw0VZdQxTB