Used vehicle with low MPG average on DIM.

[dlundblad]

When looking at a used vehicle ad and scrolling through the photos, say you see a photo of the vehicle’s DIM with an absurdly low average MPG. Is this a red flag on mechanical issues and/ or CEL’s? It tells me they disconnected the battery in an effort to reset something.

I saw an ad for what appeared to be a used nice low mileage Tacoma. The DIM displayed ~5 mpg on average. Is the dealer hiding something?

 

[PF52]

They could have disconnected the battery for various other reasons. Or maybe it was just time to replace the battery? I wouldn't be overly concerned.

 

[jeepman3071]

If it is at a dealer, my guess would be the last tank of fuel was spent moving it around the lot.

 

[Bailes1992]

If it's at a dealer then a simple software update could have caused it to reset. Couple that with lots of stop/start around the location it's at then it's more than reasonable for it to be low.

 

[atikovi]

If it's a dealer car recently bought from auction, 50% chance it had a bad battery so they replaced it. Then it just wasn't off the lot or driven very far. You really think a Tacoma only gets 5 mpg?

 

[mrsilv04]

If it doesn't tell you the entire story like this, then it might not be very helpful.
This is a 2018 GMC Sierra SLT Crew 4x4 that I bought with 43,733 miles.
Obviously it was a *very* babied truck that was never driven hard or towed with.

 

[dlundblad]

You really think a Tacoma only gets 5 mpg?

You didnt understand my question.

 

[atikovi]

I understood it fine. You thought for some nefarious reason the seller disconnected the battery to erase the check engine light and because it wasn't driven, the mpg is low. Any dealer with some brains is going to use a scan tool for that so the MPG reading isn't erased and he doesn't waste time and have to get his hands dirty messing with the battery.

 

[KrisZ]

I thought on most vehicles the average MPG can be reset manually thought the menu. I don’t think I’ve been in a car that wouldn’t allow to do that.

But to answer OP, no, that would not be a red flag to me. Even if that readout could only be reset by disconnecting the battery. Disconnecting the battery is quite normal, most service manuals call for it for pretty much any type of work, outside of regular oil changes.

 

[Skippy722]

Hiding something? Probably not, as KrisZ mentioned any disconnect of the battery is going to erase any fuel mileage data, and it doesn’t take much to get them to show that low.

My truck will show about 5mpg right after a fill up and reset of the trip meter with some gentle acceleration up to ~45mph. If it’s just getting moved around a lot or started up and ran every so often that will very easily do it, 0mph is also 0mpg.

 

[tiger862]

Hook a scanner up and look at codes. Most of the times it will show how miles driven since code was cleared. My 18 showed 3k miles since codes were cleared and only had 3200 miles on it. Sister bought an Infiniti that showed 175k, the computer showed 74k. I told her not to buy, however she bought bought it. The transmission went out 10k later.

 

[KrisZ]

Yes, if you’re worried about trouble codes, bring your own scanner, don’t rely on “clues”.