# Should i change the fuel sending unit?



## edortir6 (May 26, 2006)

Hello everyone, I got a 06 murano sl with a p0643 (fuel level sensor A high input). I changed the fuel pump (aftermarket) last year and the code went away. Just recently I had 6 new codes that I worked on 1 by 1 and was successful in fixing all but the p0643. Can someone give me direction on what to do next. Should I replace the sending unit? Is the aftermarket pump malfunctioning?


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## rogoman (Dec 16, 2004)

If you had a series of 6 fault codes at once, then you may have a problem with the *charging system or bad ground connections*. A properly working charging system puts out about 13.2 to 15.0 volts, but this is a general spec, and the factory service manual should be referenced for the correct charging system voltage specifications for a particular vehicle. A battery should have a static charge of 12.2-12.6 volts. If a battery is not good, the charging system may not be able to charge properly. If a vehicle is not charging properly and the battery is good, the first thing to do is to turn the ignition switch to the "ON" position without starting the engine and make sure the charging system warning light is operating. When a charging system is not charging, or overcharging, a lot of "strange" things can occur. It's not uncommon to see a multiple of stored trouble codes in the ECM memory. So, whenever a car is setting a multiple of trouble codes, idling funny or stalling, or anything out of the "norm," test the charging system before you start pulling hairs!

P0643 NISSAN Possible Causes:

Faulty Engine Control Module (ECM) 
ECM harness is open or shorted
ECM circuit poor electrical connection
Shorted sensor on 5 volt circuit
Accelerator pedal position sensor (APP sensor 1)
Power steering pressure sensor
EVAP control system pressure sensor
Refrigerant pressure sensor


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## edortir6 (May 26, 2006)

Thanks Rogoman. I'm going to try and get to that tomorrow. I'll post results.


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