Disconnect the capacitor from the circuit
Discharge the capacitor safely
Inspect for bulging, leakage, cracks, or burn marks
Set a multimeter to capacitance mode
Connect the meter probes to the capacitor terminals
Compare the reading to the rated capacitance
Check polarity on electrolytic capacitors
Use resistance mode to look for charging behavior
Watch for a low reading that rises toward infinity
Watch for a steady low resistance, which may indicate a short
Watch for no movement, which may indicate an open capacitor
Use an ESR meter for electrolytic capacitors
Compare ESR to the expected value
Test with a known-good capacitor if needed
Replace the capacitor if readings are out of tolerance or signs of failure are present