What maybe the fault when connecting the battery terminals wrong way round

We have a 2002 Peugeot 307 Rapier. It had been running fine but finally a day came when it started showing up anti-pollution fault. We got it checked but the local garage couldn't resolve it. We kept running the car as it would run fine but sometimes it would reset itself (I would find it out by date and time resetting back to zero). Sometimes the car would need a jump start and after that it would work fine again.

Few months down the line the battery died. We replaced the battery but connected the terminals wrong way round. We saw a bit of smoke from one of the battery terminal, upon that, we disconnected the battery and then connected it the right way round.

After that, we tried to start but the engine won't start, it would turn up but it won't start. We called the AA, they said that there might be a problem with the ECU because they can't see any response coming from the ECU. I then took it to a local garage, the checked it and told me that the ECU has gone.

I showed it to my uncle (who is a test engineer) he opened the ECU and checked the circuit. He told me that he can't see anything connection burnt or any problems with the within the circuit.

Now I am not sure what to do. Can you please help me as to

1. what can go wrong, which components may be damaged because of the wrong battery connection
2. it is worth spending money on this car

Asked on 8 January 2013 by ogenious

Answered by Alan Ross
Well firstly try this.
Disconnect the battery ( one lead) for a minute.
Then re connect BUT DO NOT switch anything on at all, and just leave for 30 mins.
Then try to start the engine.( This allows the ECU to reset itself).
If still no good then you may need a diagnostic check to be carried out ( cost about £50). if that shows that the ECU is faulty then you can remove and send it to ECUtesting .com, who will check it out and also repair it( cost approx £150)
Similar questions
My Dad has been having horrendous trouble with his Volvo XC60. He purchased it from new in June 2011. Since then it has spent many, many weeks back at Volvo. The computer system fails in part - taking...
What stop start battery would you recommend for my Skoda Octavis vRS? Prices seem hugely variable, as do warranties. How do I choose?
I own a 2018 Jaguar F type 3.0 (380) with 14,000 miles on the clock. Recently, I've started to experience battery issues. The car only does 2,000 miles a year and often spends three or four weeks without...

Value my car

Save £75 on Warranty using code HJ75

with MotorEasy

Get a warranty quote

Save 12% on GAP Insurance

Use HJ21 to save on an ALA policy

See offer