Camshaft Position (CMP) Sensor Malfunction

DTC P0420 DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0340	CAMSHAFT POSITION (CMP) SENSOR MALFUNCTION
DETECTION CONDITION	P0340 indicates camshaft position sensor circuit failure.
POSSIBLE CAUSE	CMP circuit open. CMP circuit shorted to GND. CMP circuit shorted to PWR. SIG RTN circuit open. Damaged CMP sensor. Damaged PCM.
HINT	Camshaft Position (CMP) Sensor Description Magnetic transducer. Detects the position of the camshaft and identifies when piston No. 1 is on its compression stroke. A signal is then sent to the PCM and used for synchronizing the firing of sequential fuel injectors.
Courtesy of MAZDA MOTORS CORP.

DTC P0420 INSPECTION

STEP	INSPECTION		ACTION
1	Was PCM Quick Test performed?	Yes	If engine starts, go to next step. If engine does not start, DTC P0340 is not the cause of the No Start. See TEST 16: NO START .
1	Was PCM Quick Test performed?	No	Perform PCM Quick Test.
2	CLEAR AND ATTEMPT TO RE-GENERATE DTC P0340 Clear DTCs using PCM Reset Procedure. Key ON, Engine Running (KOER). Increase engine rpm to greater than 1, 500 rpm for 10 seconds. Repeat two times. Key OFF. Retrieve Continuous Memory DTCs. Is DTC P0340 present?	Yes	Go to next step.
2		No	Fault is intermittent. See TEST 4: INTERMITTENT .
3	CHECK FOR OPEN CMP CIRCUIT BETWEEN PCM AND CMP SENSOR Disconnect PCM and CMP sensor. Install Breakout Box, leave PCM disconnected. Measure resistance of CMP circuit between PCM test pin 85 and the CMP sensor harness connector. Measure resistance of SIG RTN circuit between PCM test pin 91 and the CMP sensor harness connector. Are resistance measurements less than 5.0 ohms?	Yes	Go to next step.
3		No	Repair open circuit. Go to step 8.
4	CHECK CMP FOR SHORT TO POWER Reconnect CMP sensor. Key ON, Engine OFF (KOEO). Measure voltage between PCM test pin 85 (CMP) and PCM test pins 51 and 103 (PWR GND). Key OFF. Was voltage less than 1.0 V?	Yes	Go to next step.
4		No	Repair CMP circuit to power. Go to step 8.
5	CHECK CMP FOR SHORT TO GND Disconnect CMP sensor. Measure resistance between PCM test pins 85 (CMP) and PCM test pin 91 (SIG RTN). Is resistance greater than 10K ohms?	Yes	Go to next step.
5		No	Repair short circuit. Go to step 8.
6	CHECK FOR SHORTS IN PCM Connect PCM to Breakout Box. Disconnect CMP sensor. Measure resistance between CMP and SIG RTN at the CMP harness connector. Is resistance greater than 500 ohms?	Yes	Go to next step.
6		No	Replace PCM. See COMPUTERIZED ENGINE CONTROLS . Go to step 8.
7	CHECK CMP SENSOR OUTPUT Reconnect CMP sensor. Set multimeter to AC scale (to monitor less than 5.0 volts). Measure voltage between PCM test pin 85 (CMP) and PCM test pin 103 (PWR GND) while running the engine at varying rpm. Does AC voltage vary greater than 0.1 volt AC?	Yes	Replace PCM. See COMPUTERIZED ENGINE CONTROLS . Go to step 8.
7		No	Replace CMP sensor. See IGNITION SYSTEM . Go to step 8.
8	VERIFY TROUBLESHOOTING OF DTCs COMPLETED Make sure to reconnect all disconnected connectors. Clear DTCs from PCM memory using NGS tester generic OBD-II function. Perform PCM Quick Test. Is same DTC present?	Yes	Replace PCM. See COMPUTERIZED ENGINE CONTROLS . Repeat PCM Quick Test.
8		No	If any other DTC is present, go to applicable DTC inspection. If no DTC is present, troubleshooting complete.