Knock sensor

KEVAN TURNER

MEMBER
NISSAN

I have a 1997 villager/quest 140000 mi. It stopped dead in the road while driving and won't start. The OBD 11 flashes 3 long 4 short indicating a problem with the knock sensor. I have voltage at the conector but no change in reading when engine is hit with a hammer. Is it possible for the knock sensor to disable the engine if it goes bad. I understand that it controls the timing. When cranking the engine sounds like it's trying to run for a couple turnes after letting of the starter. Should I be looking at the timing belt? The engine has spark and spraying cleaner into the intake has no effect. I'm trying to find an easy answer before I take the top off the engine to replace the sensor. Thank you in advance for your attention to my problem.

1 Reply

RASMATAZ

CERTIFIED MECHANIC

Sir,

The knock sensor will not disable your vehicle its purpose is to retard the ignition timing when it senses a detonation/spark knock/pinging

You stated putting cleaner into the intake has no effect and also has spark. If compression and fuel were okay it should fire and start.

If its a distributor system-unclip/unscrew the D/Cap while cranking the engine is the rotor spinning? If not investigate the T belt/chain.

Rotor spinning could be a valve and ignition timing problem that's preventing it from starting up.

Check the fuel pressure and comeback.