2005 nissan altima codes p0725, po335. how to fix

P0335 Crankshaft Position Sensor A Circuit Malfunction P0725 Engine Speed input Circuit Malfunction

1. Using a scan tool, check if, when engine is running or cranking, that there is an RPM signal.
2. If there is no RPM reading, then visually inspect the crank sensor and connector for any damage and repair as necessary. If there is no visible damage, and you have access to a scope, you could check the CKP 5 Volt square wave pattern. If you do not, then, obtain a resistance reading of your crank sensor from a repair manual. (There are so many different types of crank sensors that there's no way to put here which resistance reading is correct). Then check the resistance of the CKP sensor by disconnecting the sensor and measuring resistance of the sensor. (It is best to check resistance readings from the PCM connector. This rules out any wiring problems from the start. But it does require some mechanical skill and shouldn't be performed if you\'re not familiar with automobile electrical systems). Is the sensor within resistance specs?
3. If not, replace the CKP sensor. If so, recheck resistance reading from the PCM connector. Is the reading still okay?
4. If not, repair open or short in the wiring to the crank sensor and re-check. If the reading is okay, the problem is intermittent or the PCM may be at fault. Try reconnecting and checking for RPM signal again. If there is now an RPM signal, wiggle test the wiring harness to try and induce the fault.