Starting Note

The MIL is illuminated on my 2007 Nissan Note 1.4 S with 66,000 miles. The code I get with an Autel scanner is ‘P0335 Crankshaft Position Sensor ‘A’ Circuit Malfunction’.

The engine is difficult to start and cranks for a lot longer than it should, then usually starts – sometimes you need two or three goes. Resetting the MIL extinguishes the light, but it comes back after a couple of starts. It does not appear to be generated while running, but triggered by starting. It drives OK, with no noticeable lack of performance.

I replaced the crank sensor with a brand-new one from Euro Car Parts, but it made no difference. The symptoms are exactly the same and the code returns after a couple of starts. I have unplugged the two ECU plugs as well, to check the pins and plugs, but they seem fine.

What should I investigate next? I’m aware that stretched timing chains can knock out these signals, but although I have no history for this vehicle, the oil is clean and it has a very clean air filter fitted. It also has a recent MOT, so I’m assuming the emissions are OK. Jim A poor signal from the CPS can result from a damaged reluctor ring, an incorrect crank sensor to reluctor ring air gap, or poor wiring/ connectors. If in doubt, disconnect the existing wiring from the CPS to the ECU and install your own.

If you have access to a ’scope then look at the signal received by the ECU from the CPS. If your CPS is a three-wire type then it is likely to be a Hall-effect type, giving a square wave output of either five or 12 volts. If it’s a two-wire type then a sine wave of around 1.0V is normal. Finally, it could be a faulty ECU – send it for testing first. It turned out to be a bit of damaged wiring from the sensor. I left the new sensor in place and sorted the wiring issue and the problem has now gone, with no fault codes or MIL. I also disconnected and remade all the engine earths, etc. Interestingly, the car drives a bit better, too. It just shows how hard it can be to diagnose this type of issue. Jim