Looking for a little guidance here.

I have a 2010 Sonata - runs fine, but Check Engine Light comes on and throws P0461 and P0462 codes. A few mechanics looked at it, and can't find the issue (it's not the mechanism in the tank, which they've checked and has passed).

I need to resolve the problem to pass inspection, and don't want to spend a fortunate on an older vehicle finding some short in a wire somewhere. Any ideas?

 

Because we don't know what checks they did , not wise to accept their results. After you get burned by the "Checks" other places claim they did, we learn to do our own checks and go by what we find.

I gather you are attempting to come up with some possible causes and the only suggestion I would offer is to have a shop that is on the ball or more familiar with the vehicle check the electrical connections from the grounds in the rear near the tank on up to the instrument cluster.

 

Thanks - I believe they checked the mechanism to be sure it worked, and that it was sending. The issue seems to be somewhere between that and the instrument cluster as you suggest. If I take it somewhere else to diagnose, is it generally a pretty expensive testing all the way to the cluster? Thanks.

 

Unfortunately a lot of shops don't have trained people to chase down an electrical problem.
You will need someone that has some basic electrical background to check it out. All the present shop did according to what you describe is check if it is sending the info.. If there is a poor ground the system is incomplete and it can;t work as designed. The codes are telling us that.

 

What is there in the circuit?
Fuel level sending unit, wires and connectors, power going to sending unit,
ground coming from sending unit and Instrument cluster gauge.
If the shop checked out the power going to the sending unit then check the ground
If the sending unit is working then check the cluster gauge

The DTC says that the signal is too low to input
Would think it could be frayed wires or short
But, Hanky is right. Tough to know what was done right by shop
And tough to know where to go from here
Also, suspect ground issue