Symptoms of a P020E engine code may include:
1. Engine misfire, sag, or stumble
2. General lack of engine performance
3. Distinctive odor of diesel fuel
4. Reduced fuel efficiency
Causes of a P020E engine code may include:
1. Defective fuel injection solenoid
2. Open or shorted wiring and/or connectors in fuel injector control circuit
3. Bad fuel injector
4. Engine timing component failure
5. Crankshaft or camshaft position sensor (or circuit) failure
I'd start with a simple check of the injector wiring to make sure it's connected properly and there are no shorts in the circuit. I'd do the same check on the sensor harness.
From there I personally would turn it over to a qualified tech for fuel pressure checks, injector inspection and a solenoid test.
By the way...how long has it been since you changed your fuel filters?