P1684 just means the computer memory has been cleared lately. It does not indicatoe a problem.
P0340 - NO CAM SIGNAL AT PCM
During engine cranking, after 32 crank position signals.
No Camshaft Position Sensor signal is present with crank signal.
Target magnet defective
Sensor ground circuit open
Wiring harness intermittent defect
Stray signal from the crankshaft position sensor
Irregular LAB scope pattern of CMP signal
CMP signal circuit open
CMP signal circuit shorted to ground
CMP signal circuit shorted to sensor ground circuit
8 volt supply circuit open
8 volt supply circuit shorted to ground
8 volt supply shorted to sensor ground circuit
CMP sensor defective
PCM defective (8 volt supply)
8 volt supply circuit shorted to voltage
CMP signal circuit shorted to 8 volt supply circuit
CMP signal circuit shorted to voltage
March, 2, 2009 AT 8:09 PM
That code will give you some work to do. Thats how many you should check to get that code gone.