Corsa F 1.2 Overheating issue whilst idling.

[gp9xr66]

Looking to find out why our Corsa F 1.2 petrol 5 door Elite Nav Premium whilst stationary for a brief period of time with the engine idling starts overheating, warning light on the dash comes on and I turn it off, whilst normal driving the temperature remains the same. Any ideas ?

[Cobra26]

Could be a number of things. Cooling fan coming on when idle?, Coolant level low, but should show fault for that. Air lock in system. Blockage in radiator grill, Bag/bird or ??. might be duff temp sensor. Water pump.
Question for others...does the Corsa have the open/close grill vent like the old Astra?
Certainly something that needs fixed pronto as it's running hot and may cause overheating engine damage if left.

[gp9xr66]

The brains at Vauxhall technical have indicated a full replacement of the ECU and reprogrammed at around £ 1600.00 labour & parts, what concerns me if that's not the problem ? ,then having to resort to further fault finding like what Cobra26 has mentioned, any other advise before such drastic action.

[Cobra26]

Start with the basics and eliminate the obvious. If you had a leaking tap you wouldn't replumb the whole house. Vauxhall are having a laugh suggesting that without investigating first.

[gp9xr66]

After further investigations and checking (I assume just by plugging it to a diagnostic machine)by a Vauxhall technician they have reported Fault Codes P0692-P0693-P0495-P0691, Cooling fan assembly controller circuit malfunction, recommendation purchase a new ECU and reprogrammed to the car. Again this may not rectify the problem as informed.

[Cobra26]

Does the fan come on when engine is hot and sitting idling? If not then check why not, power to fan, temp sensor for fan, relay/fuse for fan and electrical connections. I've had problems with older Corsa and got ECU exchanged to find out it was a sensor after all. My hunch is it's actually a fan problem not ECU... it's last resort. Take it to garage that will do the checks on it first. Is the coolant bottle cap on properly or leaking pressure?
Keep us posted as it's no doubt something that will crop up again if it's a Vauxhall niggle.

[gp9xr66]

I'm in the process next week to have this fully checked out by an independent auto electrician with what you have suggested, we checked the correct coolant and the bottle cap both with and without pressure, no fluid leaks, will let you know on the auto electricians findings.

[gp9xr66]

Having had the car independently diagnostic inspected, OMG firstly it came up with 19 faults relating to amperage in&output issues, it soon became apparent that in the main fuse box adjacent to the battery both the 40 amp & 5 amp fuses were blown which supplied another fuse box, as soon as these were replaced the fan kicked in, a further diagnosis cleared 16 of the faults, because of the fan failure it pressurises the A/C and that wasn't working as it dumped the gas, we checked the system for leaks and re-gassed the system, the A/C was then fully working and all the remaining fault codes were clear.
Around £200 was the cost to rectify the fault finding and re-gassing rather than the vauxhall dealer wanting to charge £1600 just to replace the ECU and NO guarantee that this would resolve the issue, unfortunately this could of been a very expensive repair with the incorrect diagnosis . thank you Cobra26 for you helpful advise.

[Cobra26]

Glad you got the correct attention in the end looks like you've found a good garage. I prefer to perceiver than part with money easily. My next concern would be how did it get to that situation. What caused the fuses to blow etc. Can you recall anything happening prior to the overheating?.

[gp9xr66]

We purchased the car from a private seller (and not the previous recorded keeper) at the time we was told about fault lights, a service (spanner) a tyre warning light ( was informed a possible TPM issue) no temperature issues with the road test and no mention about the A/C and I didn’t check myself.
I agree the conclusion is a voltage issue in-the two fuses blowing as to the cause at present as unknown.
The car was sent to Vauxhalls dealer to have a service, clear the fault codes and a safety recall ( which was a software update), little did I know 4weeks later there conclusion was a ECU change, in future an independent diagnostic will be done beforehand.