Fix a P0340 code on a Dodge Ram

Understanding the P0340 Code on a Dodge Ram

The P0340 code on a Dodge Ram is often found on the 3.6L engine. The 3.6L engine uses four camshafts and two camshaft position sensors (CMP). Each sensor is a dual-read device reading the camshaft position of both camshafts on a bank. The PCM supplies a 5-volt reference signal and ground to each CMP. The CMPs provide a digital ON/OFF signal for the intake and exhaust camshafts on each bank. The PCM uses that information to confirm camshaft positions after commanding the actuators used in the variable valve timing mechanism. In order to set the P0340 code, the engine must be running for 5 seconds and see a crankshaft signal but no camshaft signal. Once the P0340 code is set, it takes three good trips with a good CMP signal to turn off the check engine light and move the code to history code storage.

P0340 Code on a Dodge Ram possible circuit-related causes

5 volt CMP supply shorted to voltage
5 volt CMP supply OPEN
5 volt CMP supply shorted to ground
CMP signal shorted to voltage
CMP signal shorted to ground
CMP signal OPEN
CMP signal shorted to CMP supply voltage
CMP ground open

Diagnose P0340 code on a Dodge Ram

Start by checking the 5-volt reference voltage and ground to each CMP sensor with the IGN on, but engine not running. The sensors are located on the top end of each valve cover closest to the transmission side of the engine. Voltage should read 4.5 to 5.02 volts. If you don’t see those voltages, check the integrity of the wires between the CMP connector and PCM.

Next, measure the resistance in the CMP connector between the supply voltage terminal and the ground terminal. If the resistance is 100Ω or less, repair the short to ground in the CMP supply circuit.

Checking the actual CMP signal requires a scope.

If you have good 5-v supply voltage to each sensor and each sensor has good ground and you want to take a shot, replace the CMP sensor.

©, 2019 Rick Muscoplat