Without a working camshaft position (CMP) sensor, the crankshaft sensor can not define the exact position of the crankshaft drive alone. Follow this real fix to see how a faulty CMP caused a check engine light to turn on with the stored fault code, P0340.
Vehicle
2018 Dacia Duster 1.2L Petrol
Title
P0340, Replaced Camshaft Position Sensor
Complaint
The customer states the check engine light is on.
Cause
Connected a scan tool and found code P0340 – Camshaft Position Sensor “A” Circuit (Bank 1 or Single Sensor). Key on, used the scan tool to monitor the live scan tool parameters and found no obvious faults. At idle, continued to monitor the scan tool data and noticed the camshaft position (CMP) sensor displayed an intermittent signal. Raised the engine speed to 2,500 RPM and found the CMP sensor parameter remained erratic. Visually inspected the CMP sensor wiring harness and harness connector and found no evidence of any damage. Backprobed the CMP sensor signal wire, attached a lab scope and started the engine. While the CMP sensor signal was monitored on the lab scope, gradually increased the engine speed and observed the CMP sensor signal became erratic and dropped out. Continued to monitor the CMP sensor signal on the lab scope, wiggled the CMP sensor harness and observed no change in the signal. Disconnected the CMP sensor harness connector, inspected the terminals and found no faults were present. Key off, used a multi-meter to check for the presence of a short in the CMP sensor signal circuit and found no short was present. The results of these tests verified the CMP sensor was faulty.
Correction
Replaced the camshaft position sensor, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.