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Discussion Starter #1
Good evening all.
On Saturday had to call out AA as my wife’s 2009 2.0Tdi Eos battery died as we haven’t used it for over a week during the cold snap. He measured the existing battery (which we changed 5 years ago) and it was pretty much dead. He offered to put a new one on for £130 with a 5 year warranty so went for it.
Once she was fired up he noticed the ABS light stayed in orange with along with the glow plug light, what looks to be an exhaust orange light, and the red brake light flashing and beeping. He started to do numerous checks which indicate the error code 0121 communication abs error. He tried to reset it in the computer and turned the wheel full lock both ways and tried resetting again. All the same lights stayed on. He then checked a number of items, one of which was apparently a known problem with an earth near to the abs monitor. This connection was bone dry and more than tight enough. Took it for a spin around the street and also noticed that the speedo wasn’t working and the petrol gauge was erratic. All other controls on the days work fine.
He said he couldn’t do any more with his machine and recommended a local electrical expert to look into the error code further. Before I take it to them, would anyone have any further advice? He suggested that the abs module also interacts with the speedo and that if it the abs module, you can change the electrical part of it only if the mechanical side of things are ok.
Any help greatly appreciated.
Thanks
Jamie
 

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Good evening all.
On Saturday had to call out AA as my wife’s 2009 2.0Tdi Eos battery died as we haven’t used it for over a week during the cold snap. He measured the existing battery (which we changed 5 years ago) and it was pretty much dead. He offered to put a new one on for £130 with a 5 year warranty so went for it.
Once she was fired up he noticed the ABS light stayed in orange with along with the glow plug light, what looks to be an exhaust orange light, and the red brake light flashing and beeping. He started to do numerous checks which indicate the error code 0121 communication abs error. He tried to reset it in the computer and turned the wheel full lock both ways and tried resetting again. All the same lights stayed on. He then checked a number of items, one of which was apparently a known problem with an earth near to the abs monitor. This connection was bone dry and more than tight enough. Took it for a spin around the street and also noticed that the speedo wasn’t working and the petrol gauge was erratic. All other controls on the days work fine.
He said he couldn’t do any more with his machine and recommended a local electrical expert to look into the error code further. Before I take it to them, would anyone have any further advice? He suggested that the abs module also interacts with the speedo and that if it the abs module, you can change the electrical part of it only if the mechanical side of things are ok.
Any help greatly appreciated.
Thanks
Jamie
Did the AA road service person use a temporary power supply either connected to the battery cables or through the car interior power outlet when changing the car battery?

It is essential to maintain continuity of power to the vehicle control modules during a battery exchange to avoid probable loss of the settings applicable to your vehicle.

I would be very surprised if an AA road service technician did not have a temporary power supply kit for use when disconnecting/connecting batteries - our Australian road service equivalents carry a battery powered portable "settings keeper" for this purpose which can be connected to the battery leads or the auxiliary power connection inside the car to prevent the management system settings being lost when the main battery is isolated or disconnected.

You may have to get a VW service centre to reload the settings appropriate to your vehicle from the VW data system and recode others as appropriate to your vehicle.
 

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Discussion Starter #3
When he arrived he put a battery booster on to get the old battery working and turned the engine over. When he checked the battery out he said that due to the time it would take for the battery to fully charge back up (circa 8 hours) he suggested it wasn’t serviceable and a new battery would be required. Not sure if he put a temp power supply to it when changing over though?
I have attached the report below
 

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When he arrived he put a battery booster on to get the old battery working and turned the engine over. When he checked the battery out he said that due to the time it would take for the battery to fully charge back up (circa 8 hours) he suggested it wasn’t serviceable and a new battery would be required. Not sure if he put a temp power supply to it when changing over though?
I have attached the report below
I think you will find he didn't use a battery backup device while changing the battery and you have suffered accordingly especially if some time elapsed while a battery was not connected to the vehicle electrical system.

The only way of restoring your lost settings is an accredited VW service centre who can download the correct settings for your vehicle from the VW computer system.
 

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Your account of what the AA Roadside repair man did surprise me? First your problems started allowing the battery to go completely flat. That wasn't their problem but it can cause software in electronic modules to become 'Temporarily' corrupt or stuck. What they did next by connecting a battery booster to your car with a flat battery could have made the temporary software problem more permanent? AA roadside repairers usually carry professional diagnostics scanners. The moment the dash fault lights came on they should have used that tool. But the chap might have realised some damage was done and needed to make a fast getaway as you car was running, albeit with fault warnings!

A battery backup would probably not have worked for you because your battery was left to go so flat and that's a lesson you should learn - replace the battery every 3-4 years. What you needed to do was leave the dead flat battery disconnected for half an hour, then connect a new freshly charged battery NOT a battery booster and you may have got the car back with no faults. You can still try this after buying a new fully charged battery. Otherwise as Silvershadow says, your Stealer will have to use diagnostics to see if the faults will reset, or if there has been more permanent damage.

I posted back in March for members that Covid-19 restrictions and lockdowns could cause lots of problems. Even though your car is sitting idle not driven, it still has computer modules and the anti-theft system running in 'Sleep Mode'. to slowly drain the battery. Each time you start the car you need to drive at least 5 miles to replace the charge lost from starting. During Covid and travel restrictions, mileages will be low unless you are a commuting key worker. A good new battery should be able to stay at rest for a couple of months and still have half its charge left for a start. But a failing battery and cold Winter might only last 4 weeks until flat.

Wifeys VAG had a failing 4 year old battery last week. The report after she'd been using it twice a week for 3 mile shopping trips during the last 6 months was '"The starting sounds different, there's a loud clicking noise, and dash lights are all flashing."

If you keep starting (a diesel) with a low charge battery, you reduce battery life and its capacity. I recharged it and tested it's voltage drop on a battery tester. Battery voltage at 12.8 volts dropped to 10.7 volts. Tried another re-charge with same results. Replace the battery with a 75Ah 680A crank spec. New battery tested 12.8 volts after full charge and 11.7 Volts on a 200A load test.

All members laying up their cars during Covid restrictions should consider connecting a small tender 24/7 or removing the battery and keeping it on trickle charge with a Smart bench charger
 
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