I have a 1991 volvo 240 with a manual transmission. It will not start when I turn the ignition key. It happens at different times, sometimes in the morning when you first go to start the vehicle or after I have driven the car for a while. The battery is only 4 months old, the selenoid does not click and the starter works normal 90% of the time. I pulled a code of 214 of the computer, RPM sensor has intermittent signal. The book says this could cause an intermittent start. I replaced the sensor but still have the same problem. Any advice would be appreciated. Thank You.

"It will not start when I turn the ignition key...The battery is only 4 months old, the selenoid does not click and the starter works normal 90% of the time...code of 214 of the computer, RPM sensor has intermittent signal. The book says this could cause an intermittent start..."

It sounds as if you're mixing apples and oranges. Do you mean it doesn't crank when you turn the key, or do you mean that it cranks over but won't fire up and run?
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Don Foster (near Cape Cod, MA)

The engine will not turn over. When the starter cranks the car starts fine.

This sounds very much like a defective (intermittent) solenoid, defective (intermittent) ignition switch, bad connection at the solenoid or in the harness, or some similar electrical fault. It begs to be solved using simple and straightforward electrical troubleshooting methods (meters, test lights, circuit jumping, and so on).

I do not think it's related to a crank sensor or similar.
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Don Foster (near Cape Cod, MA)