QuestionKMHDN45D62U252543. P0340 CODE PRIOR TO CYLINDER HEAD WORK. AFTER CYLINDER HEAD WORK COMPLETED SAME CODE RETURNS. CAM AND CRANK SENSORS HAVE BEEN REPLACED. TIMING DOUBLE CHECKED. CODE RETURNS AFTER 2ND KEY CYCLE. ON LAB SCOPE NO PATTERN RECEIVED ON THE CRANKSHAFT SENSOR. ALTERNATOR AND GROUNDS AND PCM HAVE BEEN CHECKED. ANY IDEAS?
AnswerFirst, check the installation of the cam sensor. There's an o-ring on the sensor to prevent oil leakage around the sensor. If the old o-ring remained in the sensor hole and the new sensor was installed with a new o-ring, then this may keep the cam sensor far enough away from the camshaft to cause there to be no signal.
Next, consider that this engine is set up so that the crankshaft drives the exhaust camshaft via a timing belt, and then the exhaust camshaft drives the intake camshaft via a timing chain under the valve cover. The camshaft sensor reads a dowel pin in the exhaust camshaft, so it's not sufficient to check the timing just at the camshaft sprocket; whether the intake cam is timed properly to the exhaust cam must also be checked.
If the above checks okay, then check as follows:
1. Make sure the sensor dowel is in the intake camhshaft
2. Check that you have battery voltage between the outer pins in the camshaft position sensor connector when the ignition is on.
3. Check the continuity of the signal wire (center pin of connector) to the ECM and verify that it's not shorted to ground.
Lastly, I'll say that the vast majority of head work done to Elantras is due to overheating. In numerous cases, the overheating causes damage to the cam sensor, requiring replacement of the sensor.
