Urgent advice request - catalytic converter warning light

[trailtrotters]

I am hoping for advice please as to the plausibility of a correct diagnosis of the need to replace the alternator following the display of a catalytic converter fault warning light on the dashboard.

Background information:

2016 Ocean T6 - owned by us from new and fully maintained in accordance with schedules and advice from the dealer with whom we have always had a good relationship. Unfortunately they are so overloaded with work that they were not able to check our warning light for over 2 months. Hence we booked it in with a local VW Specialist who today diagnosed it as requiring a replacement alternator at the cost of over £700 (using a new VW part). They asked if we had ever had a problem with a flat battery - we said no. We agreed to return it the day after tomorrow and came home and looked up what the alternator was all about.

We are very puzzled to see the list of symptoms for needing to replace an alternator as we have not experienced a single one of them. No issues with brightness of lights or starting the vehicle, it never stalls (other than automatic stop/start), electric windows etc all work in a timely fashion, no battery warning lights.

We have only driven 27,000 miles of which 1,900 was in 2 weeks this May and 1,600 in 3 weeks this July. However we make a point of taking it out for short trips on a regular basis and plug in the electric cable for a few days at home every month if we have not plugged in at a campsite to keep the leisure batteries in good condition, never had an issue with them.

Our concern is that we will spend £700 to fix a problem which does not exist. If it were not for the catalytic converter fault warning light we would not think there was anything wrong at all. Any observations tonight or tomorrow morning would be greatly appreciated.

 

[dspuk]

While it cannot be discounted, for some reason, their testing shows up that you need a new alternator (which I doubt) I can't see what that has got to do with the Catalic Convertor. It's like saying you need new tyres because your alternator warning light is on.

You have a cat warning light - so I'd focus on that. Lots of short trips are very indicative of not getting it hot enough to burn off the nasties, even if you throw in the odd long one.

I'd not be paying it but taking the van for a long hot thrash down a motorway. You could also get the Carista and trigger a recycle on the Cat and then go for the drive.

Maybe there is something specific about a Cat and an Alt that has changed since I mechanic-ed....

 

[Ozzy Pete]

I would say that if you are not going on any long trips for the rest of the year with fear of breaking down in the middle of Spain or similar and that you have the right breakdown cover. I would leave it and see what happens.

 

[Kayleigh]

Can you post a photo of the light?
When does it come on?
Is it flashing?

 

[trailtrotters]

Can you post a photo of the light?
When does it come on?
Is it flashing?

Comes on as soon as we switch on the engine and stays on permanently. Does not flash.

 

[Stu@rt]

Engine management light, can be for any number of reasons. Its not specifically a Cat warning light. One of dozens of sensors has reported a fault. Dealer will have plugged in via OBDII port to get a fault code to aid investigations.

 

[trailtrotters]

Thank you very much indeed everyone for all of your very helpful replies which have enabled us to decide this evening what to do. We will call the garage first thing in the morning with a view to cancelling any further work, take our planned trips over the coming weeks which will involve motorway driving, but will not take us further than 100 miles from home, then discuss it with the dealer when they can free up a slot for us.

It is so very helpful to have such kind Cali folk available and willing to offer advice and information at such short notice. Thank you again.

 

[dspuk]

Engine management light, can be for any number of reasons. Its not specifically a Cat warning light. One of dozens of sensors has reported a fault. Dealer will have plugged in via OBDII port to get a fault code to aid investigations.

Ah. Engine management light. Makes more sense then. Could still be worth getting the Carista and checking the fault code yourself.

 

[Kayleigh]

Ah. Engine management light. Makes more sense then. Could still be worth getting the Carista and checking the fault code yourself.

Yes, or can the AA check if you’re a member? It could be a multitude of things. I had a faulty sensor causing this light to come on, but I would probably like to know the cause before driving long distances.

 

[dspuk]

Yes, or can the AA check if you’re a member? It could be a multitude of things. I had a faulty sensor causing this light to come on, but I would probably like to know the cause before driving long distances.

I guess they could - but not all may have the VW specialist software. When you call them out under Euro cover it is always good to ask for a VW specialist trained one. Carista will give you the code and plenty of forums have them listed. 25 quid from Amazon, next day delivery, first month free. At least then a conversation you can lead, rather than follow.

 

[Perfectos]

If your alternator was kaput it’s likely this light would be lit up (battery light)

its highly likely that your Engine management light is from short journeys.
try driving for 30 minutes with revs above 2500 for the entire 30 minutes.

if that fails to fix the issue, call vw assist (join if you need to ) ,, they will either sort the issue or tell you what the issue is and either deliver it to the dealer or if you can drive it without making the issue worse, they will get it booked into a dealer (your dealer) as a priority (vw assist / AA have priority at a dealer)

 

[trailtrotters]

Thanks again, all very useful suggestions.

 

[Stu@rt]

Thanks again, all very useful suggestions.

Let us know how you get on today

 

[vbk1975]

Comes on as soon as we switch on the engine and stays on permanently. Does not flash.

View attachment 114276

Lots of reason this light could be showing, but agree a failing alternator would normally put a charge warning light on.

This might be worth a thought.

We had a cracked rear EGR exhaust pipe on our 17MY T6 204, it is a really common fault (discussed in lots of places) and it resulted in this light for us, based on a EGR fault code.

Our fault started with a slightly louder exhaust noise from outside the van, no warning light and then a slight exhaust smell. Van stalled few times from cold, moving on the drive and then after a trip to Dover (~200 miles) the warning light appeared.

It is really difficult to see the pipe, but a small crack between flange and pipe underneath.

 

[trailtrotters]

Good evening again. Thank you for the cracked exhaust pipe information vbk1975 something useful to be aware of but we do not recognise any of those symptoms at the moment.

Stu@rt you asked me to let you know how we got on today. Our early morning call to the garage was fine to cancel the alternator replacement task and agree what we owed them for yesterday. Although to our minds the warning light displayed matches the picture beside the explanation of 'Lit up or flashing: catalytic converter fault' on page 17 of our Edition 04.2015 of the Owner's manual, during our brief conversation with the mechanic today he was talking about the display having 3 dots and referred to the Engine Management Light which seems to accord with the comments made by some of you in the thread above.

Having never heard of Carista, we watched a You Tube video today and now have a notion of how that could be of assistance if we are brave enough.

 

[Tocosan]

My engine warning light was triggered by foxes eating the wires under the van. The wires were those that connected to the NOX sensor and the Adblue sensor. Worth having a quick look under the van to see if there is any obvious damage, especially if you live in an area that has wildlife. Mice also go for the wiring, which I am informed contains soya in the insulation and can smell like food to them (I have not verified that last statement).

 

[trailtrotters]

Thank you for sharing your experience, indeed we have foxes and recently a bold as brass unwelcome large rodent in our garden. We blame most general overnight damage on the badgers but doubt this could be them. We will take a look at our wiring tomorrow.

 

[trailtrotters]

Hello again to those who kindly provided input to this thread back in the autumn. It was my intention to update you with the outcome but regrettably we have no progress to report so thought we would share our current situation in the hope of avoiding a potential large bill.

To recap, we followed the suggestion from Perfectos on 11 September, courtesy of our nearest motorway, the Engine Management Light stayed on. We have not felt confident enough to go for a Carista as proposed by dspuk as all we can do is report the results to a professional. There was no sign of rodent damage.

We still had our investigation appointment booked with our regular VW dealer for 20th October so decided to wait for that. However that was far from satisfactory with their invoice stating as follows:-

"Multiple Lights have shown up on dash in amber. Confirmed EML on dash, connected and found codes relating to low voltage. Carried out checks to alternator and found all functioning correctly and battery checks all ok. Suggest battery to be charged or replaced."

The EML was not displayed when we left the garage but came on after a supermarket stop about 8 miles away. Having returned to the garage they recommended we go home and trickle charge the existing battery. We did this but still the EML displayed so we booked the next available appointment with them for the whole day yesterday (23 January). Their conclusion is that an error with the Engine Control Unit is being reported, for which they need 4 hours labour authorised for investigation which could result in either wiring work or a replacement ECU part for which they quoted £1,750 inc VAT. We have reserved a spot for 12/13 February but feel the whole escapade is becoming ridiculous and we can foresee shelling out £2,150 and the EML then coming back on the next day. Our trusty and well maintained low mileage Cali continues to perform brilliantly with no discernible problems whatsoever so we are feeling at a loss of what to do which is not like us.

Further suggestions would be greatly appreciated.

 

[Silverace_Junior]

Fault codes related to low voltage are wiring related in the majority of instances, the most common culprits being loose or corroded ground connections. Only rarely will an ECU have internal issues that result in a low voltage DTC. What the ECU is telling is that at some point the voltage level at a certain or multiple terminals is lower that the required minimum threshold at that terminal in the present operating conditions. Any good shop should be able to check the wiring and voltage levels in those operation conditions and determine the root cause of the low voltage in the circuit concerned.

 

[Silverace_Junior]

Oh, and inline connectors in the wiring harness with moisture in them (and resulting corrosion and resistance) are also common root cause of such DTC’s. You’ll most likely have to give them (and pay for) some time to do proper diagnosis.

 

[Perfectos]

Charge the battery as suggested (24hrs on a decent smart charger)

check all earth connections engine bay, battery & under drivers seat / carpet between seats.

edit : is the carpet damp in the footwells / between seats, corrosion could be an issue with a earthing point

edit: has the van had updates applied to the software? (There have been quite a few for T6)
Implausible errors can be caused by software and throw all sorts of faults.
have the dealer hook the van up to the mothership to apply all software updates, the cost should not be too much as it requires minimal Labour, it’s literally an upload & download to / from factory. Updating the software will not hurt and may fix some / all of the issues.

 

[Perfectos]

If your ECU is suspect ?

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I have no experience of either company , simply plucked from tinternet

 

[trailtrotters]

Many thanks Silverace_Junior and Perfectos both very helpful.

We telephoned Mendip Auto Electric this morning who suggested we would be better trying another vehicle electrical specialist nearby. We have an appointment booked with them for Friday 2 February and will let you know the outcome.

 

[vbk1975]

Many thanks Silverace_Junior and Perfectos both very helpful.

We telephoned Mendip Auto Electric this morning who suggested we would be better trying another vehicle electrical specialist nearby. We have an appointment booked with them for Friday 2 February and will let you know the outcome.

@trailtrotters - I would suggest they check the small plug to the alternator as a start, the Alternator talks to the engine management and if this connection is broken, then the alternator will still charge at a fixed voltage but the engine management will see it as fault as it is unable to change the charging voltage and get feedback from the alternator. The plug and wiring can get damaged when working on the engine, cambelt changes, tensioner, etc etc

 

[trailtrotters]

@trailtrotters - I would suggest they check the small plug to the alternator as a start, the Alternator talks to the engine management and if this connection is broken, then the alternator will still charge at a fixed voltage but the engine management will see it as fault as it is unable to change the charging voltage and get feedback from the alternator. The plug and wiring can get damaged when working on the engine, cambelt changes, tensioner, etc et