Warning light on after agreeing trade in - will the dealer reduce the offer?

[Whyismycatanasshat]

I am collecting a new to me car on Saturday. The dealer has offered me a low trade in (£2000) for my current car which has come to the end of its lifetime with me due to ongoing repairs. It was running fine when I agreed the trade in, no warning lights etc.
However today I drove through a long, shallow puddle - an actual puddle I’ve driven through millions of times - not a flood, and the check engine light has come on.
My local garage say it’s a soft fault, possibly due to it getting wet and to pop in tomorrow and have it diagnostic checked. They know it’s being traded in.

If the light is still on on Saturday, how likely is it the dealership will reduce the trade in?

I have another thread running about how I’m grieving and trading in this car is painful so please go easy!

Just get them to reset it, or buy a code reader on line and do it yourself. Hand it in. Done.
0 guilt.

Ime they won’t even look at it again. Fingers crossed for you.

They will look at it again and if a warning light is on then they will reduce the offer. I know this from experience, what I was told is get it checked and the issue resolved before trading in.
Even if you reset it before you go in, there’s a high chance that the light will come back on when the sales advisor checks the car or moves it to the back.

It won’t if you don’t tell them!

The same thing happened to us with our most recent trade in , warning light came on the day before trading in after a price was agreed . Told the garage when we got there , they didn't reduce the agreed price. They already knew there was other work needing doing , hence us changing cars . I guess there's no hard and fast answer, but I felt better not hiding it from them . After all if there was a fault with the car we bought I would have been straight back to them.

Thanks for everyone’s experiences, I will tell the dealership if the light is on and take it from there,

The local garage has run a diagnostics program and it’s another electrical sensor gremlin. Not worth me repairing it before trade in apparently; the mechanic has reset the check engine light but warned me it may come back on.
He doesn’t think the dealership will care either way.
When I asked how much fit the diagnostics and his time, he said if I nipped to the bakery across the road and got him a coffee on his account we’d be even as he’s on his own today.
There are some good people about - both him and the other mechanic have been great this last year.
Needless to say, I bought him a coffee and the cake the bakery said he was fond of.

For anyone googling this in the future -
the dealership didn’t look at the car at all and before we’d even left the dealership with the new car they’d transferred ownership of the old one to themselves.

Had the light come back on or not?

@PodMom Yes, but only after another wet drive on Friday. The car was running perfectly the whole time which lends itself to the garages theory that one of the dodgy sensors doesn’t like the rain.

Oops, I really should have added that to my update post!

At that value it is going straight to auction. Dealer probably won't care.

Probably out of the question, but would it be worth getting an OBD2 scanner? The onboard computer will have logged the fault. An OBD2 scanner plus Google = enlightenment, and then can assess more easily how the car will be dealt with, ie auction or trade-in.