Mechanic changed cam crank sensor & disconnected positive battery cable- "reset" it; but came back on. Doesn't know how to "resynchronize" it (can't find software on machine).

with the key in the "on" position (not started/running) take off the NEG cable from battery and touch it to the positive terminal of the battery leaving it on there for about 5-10 mins, reconnect neg cable to battery and then start vehicle your check engine light and computer should be reset. Works for any vehicle. Good luck.

cam sensor fail can be crank sensor fail engine will run with cam sensor fail but crank it will not fire. also recheck the timing belt settings you fit the timing belt and run engine till warm then recheck the belt adjustment to make sure its in line and at recommended tightness.

timing belt is off by a tooth or two. you probably didn\'t have to replace the coolant sensor; that code sets whenever the sensor is disconnected and the ignition is turned on; and it needs to be reset by disconnecting the battery or with a code reader. anyway, the crank/ cam sensors are out of sync. if you\'ve got the twin cam engine, they are a royal pain to get the belt to lay properly on the two cams.

Check connections to crank sensor, then reset your comp by disconnecting your battery cables and holding them together. Make sure to have the code cleared as well.

P1391 (M) Intermittent Loss of CMP or CKP Loss of the Cam Position Sensor or Crank Position sensor has occurred.

P0340 is cam position sensor. P1685 is for the key(has a chip in it) P1684 is battery has been disconnected. If the engine will still crank then codes P1684 & P1685 are probably old codes. So if the car will still crank, lets forget about those codes and focus on P0340 A bad cam position sensor will cause the engine to die and not allow it to start back up. Replace the cam position sensor and clear the code and the car should start up.

reset the computer ... by disconnecting the battery competely (positive AND negative) AND LEAVE IT DISCONNECT FOR ABOUT 20 MINUTES. Then turn everything OFF in the vehicle (AC, Radio, etc....) reconnect Negative terminal first then positive. Don't crank it yet!! Turn the key to on position and leave it there for 1 minute..then off for 1 minute... Do that 3 times. No crank it up. If still no fire you need and ignition module.. get a refund on the cam sensor..they rarely are the problem.. (even though the diagnostics seem to point a finger at them quite regularly).... One last thing DON'T GO PAYING FOR A NEW MODULE...Call a scrap yard and they each probably have a room full of them.. cost you say $20-$40. Hope this info helps!

You haven't given any vehicle information, but you should be able to disconnect your battery at both the positive and negative, and hold the two cables together for a few minutes, and then reconnect. If that doesn't reset it you may have to have it reset with a scanner.

The crank sensor is located on the engine near the flywheel axis of the crankshaft.

Crankshaft Position Sensor Removal & Installation To Remove:
Location of the crankshaft position sensor on the 2.4L engine
Location of the crankshaft position sensor on the 3.0L engine
Location of the crankshaft position sensor on the 3.3L and 3.8L engines
NOTE: On the 2.4L engine, the crankshaft position sensor is mounted to the engine block behind the alternator, just above the oil filter. On the 3.0L, 3.3L and 3.8L engines, the crankshaft position sensor is mounted on the transaxle housing, above the vehicle speed sensor.

1. Disconnect the negative battery cable.
2. Raise and safely support the vehicle.
3. Disconnect the crankshaft position sensor electrical connector.
4. Unfasten the sensor mounting screw, then remove the sensor from the vehicle by pulling it straight out.

To Install:
NOTE: If the sensor removed is going to be re-installed, clean off the old spacer on the sensor face. A new spacer must be attached to the sensor face before installation. If the sensor is being replaced, be sure that a paper spacer is attached to the sensor face.

1. Install sensor and push the sensor in until contact is made. While holding the sensor in this position, install and tighten the mounting bolt to 105 in. lbs. (12 Nm).
2. Connect the crankshaft position sensor electrical connector.
3. Lower the vehicle.
4. Connect the negative battery cable.

2.0L 2.4L Removal The camshaft position sensor is mounted to the rear of the cylinder head.

Remove the negative battery cable. Disconnect the PCV hose and reposition Disconnect electrical connectors from the camshaft position sensor. Remove camshaft position sensor mounting screws. Remove sensor.Loosen screw attaching target magnet to rear of camshaft and remove magnet.
Instalation The target magnet has locating dowels that fit into machined locating holes in the end of the camshaft.
- Install target magnet in end of camshaft. Tighten mounting screw to 3 Nm (30 in. lbs.) torque. Over torqueing could cause cracks in magnet. If magnet cracks replace it.
- Install camshaft position sensor. Tighten sensor mounting screws to 12.9 Nm (115 in. lbs.) torque.
- Carefully attach electrical connector to camshaft position sensor. Installation at an angle may damage the sensor pins. - Connect the PCV Valve hose. - Connect the negative battery cable.
2.7L V6 Removal
The camshaft position sensor is mounted in the front of the head.

Disconnect electrical connector from sensor. Remove camshaft position sensor screw.
CAM Sensor Location 2.7L
Without pulling on the connector, pull the sensor out of the chain case cover.

Installation - Install sensor in the chain case cover and push sensor in until contact is made with the boss on the head. While holding the sensor in this position,install and tighten the retaining bolt to 12 Nm (105 in. lbs.) torque.
- Attach electrical connector to sensor.

Good luck and hope this helps

I had the same problem with my '05 Stratus SXT 2.4 DOHC. I've replaced the cam pos sensor and it seems to be running fine right now. On the Dodge forums a lot of the guys say that you need to replace the crank pos sensor too. I've bought one of those just in case it comes back again. Hope this helps.