Q:

Couldn't start my Volvo due to Key Error. Called assistance and he fixed it by hitting the key with a screwdriver. What could be the error?

My Volvo S40 (06) would not start when I turned the ignition key. I got a message that was somewhat like "Key Error, please try again". I tried with both my keys so it wasn't the key itself. I think I could hear some relay clicking in the on position. I had the same error about a week earlier but then it worked after a few tries and I didn't think more of it, but this time it would not work.
I called the Volvo assistance and the guy they sent put the key into the ignition, turned it fully on and hit it relatively hard about ten times with the handle of a screwdriver, then he turned it to the off position and repeated the procedure.
The car then started. He said that he had fixed this problem on a few Volvos and they seemed to continue working after this, but he could not guarantee anything.
I am not a mechanic (obviously) so I wonder if someone knows what this error could be. Is it just oxidized connectors or is it a symptom of some bigger problem? What can I do about it?

A:

I recently had a similar problem where I got intermittent "Immobilizer" messages.
According to my mechanic (20+ years of Volvo experience) the connector between the antenna ring and the wiring harness sometimes causes problems - taking it off, spraying it with contact cleaner, and re-seating it fixes these.  It could be that the vibrations from hitting the key were enough to overcome the resistance and allow the key to be recognized & the car started.
It's a relatively simple job to get to and clean the connector, which might be good preventative maintenance.
Other possibilities:  You could have a bad relay.  There's a fusebox under the hood, and one of the relays (R13) is for the starter.  You should be able to remove the relay, and jumper the connection to determine whether or not the relay is the problem.  You can get the wiring diagram for the car here.
Finally, you could have an intermittent connection to the starter, or a bad starter.

A:

If you had given that description without the screwdriver part, it would sound to me like your car is one of those that has a chip in the key where not just any key matching the physical cut will work, it has to be in combination with the car reading the chip.  The goal being more security to keep someone from getting a hold of your key and making a copy of it or trying to circumvent the physical portion of the ignition.
These were the precursor to the keyless ignitions that are found on more and more cars these days where you don't even have to put the key in, just have it in your pocket.
Perhaps the transmitter/receiver is in the steering column as the key would be in the ignition when it is trying to read it and hitting the key in the ignition caused enough vibration to jossle the transmitter/receiver.  Volvo may have had a manufacturing issue on that model of a weak soldering joint or similar causing an intermittent issue to develop over time.

A:

I don't know why he would beat on your car, as the problem will likely just return. The problem likely lies in one of these places: The tag in the key itself (RFID) read by the computers, the ring that provides the field required to read the tag, or the computer that recognizes the tag. Beating it fixes nothing.

