Car developed an engine fault last night, (seems to be running on 3 cylinders)It’s got 11 months MOT, but the wife doesn’t like driving it so it’s probably going to be replaced. What do people reckon, spank more
Money on it before I sell it, or just sell as is. 1.9tdi A4 avant with 140k on the clock

Get a diagnostics done on it to find fault, cost £50 max, then make decision.
Problem with cars these days is a £2.50 part failure sends it into limp mode!!
I had a problem on mine and they instantly said, ‘new turbo’ £800+!!! Thankfully the mechanic was old school and was convinced it wasn’t and it turned out to be a sensor on the fuel system that cost £7.50.

^^ sensors are well used routes to jack up a repair bill. OP make sure you take the car to a good independent, maybe more than 1 garage too. If you don’t diagnose the fault any buyer will assume the worst and you’ll get minimum price.

Do you have a neighbour/friendthat has an OBD2 scanner you could borrow? hey can be picked up for around £10/£20 so not a bad investment.

Plug it in (usually driver’s footwell in VAG cars) and see what fault codes it throws up, it should at least give you an idea of what the problem could be.

Best case it’s a cheap fix, worst case it’s more serious and it goes as spares/repairs.

A bluetooth OBD2 reader should be part of everyones toolset now imho. £5 to buy, a free phone app and you’re done.

Saved a colleague getting fleeced when all his car needed was one new coil pack.

Plus if you get bored you can run a HUD on it and pretend you have a super posh car.

OP agree with the above…get a diagnostics done on the car but make sure its a proper VAG machine so the fault code comes up clearly. some of the non VAG machines wont be able to pinpoint the exact fault code
my audi a6 (when i had it) also went into limp mode…the auto box wouldnt shift past 2nd. audi reckoned it was one of the 2 ECU’s which would have cost 1k each to replace. couple of other places reckoned the gearbox had had it after 110k
my local garage ran a diagnostic on it that said it might have been a shift sensor but the code was vague. he recommended another place that had the proper VAG diagnostics machine. turned out to the the gear shift ratio sensor which cost £25 to replace!!

Next time don’t buy an Audi, I had the same issue with mine. Intermittent air leak fault, cleared the fault and prepared to sell it cheap it it gets picked up.

OP just a follow up and to endorse gonzy, the Audi main dealers are terrible at exaggerating work. Our A6 was trouble free over 120k although not if you listened to the dealer, call me suspicious but we had a couple of fault codes appear after taking the car for a service – one example audi quote £2.5k, local garage £50 to reconnect a loose control rod.

Google for a local Bosch diagnostics centre 😉

“A bluetooth OBD2 reader should be part of everyones toolset now imho. £5 to buy, a free phone app and you’re done.”

Useful for a pointer in the right direction but over all quite a crap solution for most cars.

Getting the proper software(lexia/peugeot planet in my case) for my car has made life so much easier – generic OBD readers are only slightly better than the parts cannon IME

If you’re near Cardiff or the SW I can read it for you with my VCDS.

Getting the proper software(lexia/peugeot planet in my case) for my car has made life so much easier – generic OBD readers are only slightly better than the parts cannon IME

Doesn’t all this proper software and cabling cost 100’s of pounds??

Not necessarily.

A genuine VCDS does cost upwards of £250 now, but for Toyota you seem to be able to download their software easily and use it with a generic OBD cable and I’m not sure how illegal or immoral it is.

It could be a really easy fix. Coil pack? Sensor? Connection loose? Spark plug?

You’ll be bid peanuts in this state. Get it sorted.

Slight digression, but I had a Freelander that would not start. “Specialist” came out did tests and told me new injectors required (£75). Injectors fitted by myself (£600) car still did not start. Turned out it was a £2.50 o-ring on low pressure fuel sensor.

depends on the car.

for me it was 70 quid.

70 quid well spent.