Note on Intermittents

INTERMITTENT CONDITIONS
If the Warning Lamp flashes a diagnostic trouble code as intermittent, or if after a test drive a DTC does not reappear though the detection conditions for this DTC are present: the problem is most likely a faulty electrical connection or loose wiring. Terminals and grounds should always be the prime suspect. Intermittents rarely occur inside sophisticated electronic components such as the Control Unit.
Use the DTC information to understand which wires and sensors are involved.
When an intermittent problem is encountered, check suspect circuits for:
1. Poor terminal to wire connection.
2. Terminals not fully seated in the connector body (backed out).
3. Improperly formed or damaged terminals.
4. Loose, dirty, or corroded ground connections:

HINT: Any time you have an intermittent in more than one circuit, check whether the circuits share a common ground connection.

5. Pinched or damaged wires.
6. Electro-Magnetic Interference (EMI):

HINT: Check that all wires are properly routed away from spark plug wires, distributor wires, coil, and generator. Also check for improperly installed electrical options, such as lights, 2-way radios, etc.