Warrior193

Provided your vehicle does not have automatic Stop-Start and the battery physically fits the battery clamps, that's fine - your new battery just has a larger capacity and higher cranking current capability.

Your error with the negative charging lead will not be the cause of the auxiliary belt squeal - get the belt tensioner and belt checked.

@willliamm can you post an image of your left-hand control stalk so that we can identify what type of Cruise you have?

I'd suggest getting it properly tested - preferably by somewhere not primarily focused on selling you a new battery. An accurate test really requires the battery to be charged to 100% first, which may not necessarily be the case with these smart alternators.

Has your battery actually been load tested?

I'd say that it looks like one of the assist programmes (either front or rear) It does look like part of a rear camera image.

A plug-in digital voltmeter in the 12 volt socket will allow you to monitor the alternator output, it should register something over 14 volts on braking overrun or when battery is loaded (lights, fan, steering etc)

Your short trips might be part of the problem, but I've seen quite a few posts regarding insufficient charging for the Mk4 12 volt battery on the forum.

Hello Martyn, welcome to the forum. I can't help with the erratic idle, but can recommend a garage in New Malden if 8 miles is not too far. Chamberlains, just off the A3 at the Kingston flyover/Shannon corner. I used to use VAS Technical, but they moved to Ashtead, a little too far away from my area.

Are you referring to the red seatbelt warning in the tacho - or the white line diagram on the Maxidot display?

For a UK registration vehicle, the 3 or 4 character prefix to the engine number on your V5 document is the engine code - it is also listed on the B pillar label.

Are you able to access the rear of the cluster to check?

For the rear fog light, provided the light fitting is fully-lamped, I believe there is an adaption to enable both rear fogs (Scandinavian, I think) - although access for adaptation may require Stealer or similar to bypass protection.

... and if they still strongly disagree with you, you're a mile away from them - and you've got their shoes!

Hello, what engine do you have and what's the problem you're getting?

If the tank is fitted with a carbon breather canister, doing this is not recommended - recommendation is to stop pumping on 'First Click' of nozzle shut-off.

I agree that a faulty or insensitive tank sensor could be an issue - recommend a few more fills of the tank to see if the apparent errors continue, running the tank well down - with the back up of spare fuel just in case.

AFAIK, the fuel usage computations are made either from fuel pump-stroke data or sensors in the fuel delivery line - I presume range is calculated from measured tank contents (tank sensor) divided by current usage rate.

... Unless the fuel gauge and range computation errors continue until the tank is actually empty.

Hello, welcome to the forum. While it is usually the case that the fuel gauge remains at 'full' indication for 50 to 70 miles after completely filling the tank, it would appear unusual to me for it to stay there for more than 200 miles! Is your tank capacity 60 litres on the Superb? I'd consider carrying spare fuel in a decent can and try running the tank down further to check whether the gauge and range computations start to agree.

Until you get to the bottom of this, seriously consider disconnecting the battery while car is not in use - continued deep discharges are very bad for your new battery. At 10.5 volts, battery is completely discharged.

Is it possible that the heater aux pump is trying to pump against the normal coolant flow direction?

That suggests that there's a parasitic drain somewhere - to identify what is causing it will require an ammeter in series with battery lead (or Amp-clamp meter) and disconnecting possible loads. I don't know if your vehicle has can bus wiring. Do you have heated mirrors, seats or rear window?

Hmm, defo not a specialist or dealer install! Have these battery issues occurred since the wiring removal?

Thanks, that would seem to indicate the alternator is charging ok. Next thing to check is that everything is actually switching off when the ignition is switched off - check interior and exterior lights including trunk light. Is the infotainment system original, have any changes or additions been made recently?