service engine light & codes

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Dave - 17 Apr 2008 04:14 GMT

Have 99 maxima, check engine light came on today. Took to auto-zone, codes
read po325- knock sensor, and po303- number 3 cylinder misfire. Where
exactly is knock sensor located & is it hard to replace. Price quoted was
$176 for sensor. Print out says # 3 cylinder could be wire, plug, vacuum
leak, injector. Might have local mechanic check that out, but was wondering
if I could replace knock sensor to save a little labor cost. Thanks for any
help and info.

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E Meyer - 17 Apr 2008 17:44 GMT

On 4/16/08 10:14 PM, in article 4806c08d$0$3352$4c368faf@roadrunner.com,

> Have 99 maxima, check engine light came on today. Took to auto-zone, codes
> read po325- knock sensor, and po303- number 3 cylinder misfire. Where
[quoted text clipped - 3 lines]
> if I could replace knock sensor to save a little labor cost. Thanks for any
> help and info.

Don't worry about the knock sensor code until you get the other problem
fixed. It could have been set by the misfire. After everything is fixed
and reset, then read the codes again to see if the knock sensor returns (it
will not set the engine light if it is the only code). Only then do you
want to waste the time & effort to replace it.

The knock sensor is located under the intake manifold approximately dead
center on top of the engine. If you have access to somebody with really
tiny hands who can reach up in there, then it can be replaced easily.
Otherwise, its a real pain.

Bottom line - whatever your problem is, the knock sensor did not cause it.

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Dave - 18 Apr 2008 01:40 GMT

Thanks for info E Meyer. Car quit on me not long ago, wouldn't crank.
Mechanic said computer had went bad in his opionion cause everything else
checked out. Long story short, it was ignition key. Had key made at local
key shop, not nissan orginal. Lost original key afterwards, so was using
duplicate. Had to have the orginal key made at nissan dealership, $125
bucks. Just got car back from shop last week, been running great, but every
now & then, not often, would skip just a little. Will have plugs, wires,
coil, checked. Does it hurt anything to drive car when it only skips
occasionally. Will be few days before can check it out good. Thanks

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E Meyer - 18 Apr 2008 15:29 GMT

On 4/17/08 7:40 PM, in article 4807fc6c$0$7696$4c368faf@roadrunner.com,

> Thanks for info E Meyer. Car quit on me not long ago, wouldn't crank.
> Mechanic said computer had went bad in his opionion cause everything else
> checked out. Long story short, it was ignition key. Had key made at local
> key shop, not nissan orginal. Lost original key afterwards, so was using
> duplicate. Had to have the orginal key made at nissan dealership, $125
> bucks.

That's one thing I still enjoy with my '96 & '97 - no chip in the key. The
$2 copies from Home Depot will actually start them.

> Just got car back from shop last week, been running great, but every
> now & then, not often, would skip just a little. Will have plugs, wires,
> coil, checked. Does it hurt anything to drive car when it only skips
> occasionally. Will be few days before can check it out good. Thanks

Shouldn't hurt anything.

Btw: it doesn't have a coil and wires, it has a separate coil over each plug
and there are no conventional spark plug wires. One thing you might try is
to switch the coil at the cylinder with the misfire with one of the other
ones and see if the misfire code moves with it. That would be a big hint.

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NissTech - 19 Apr 2008 01:41 GMT

Ignore the knock sensor code and replace the coil pack for #3 cylinder

> Have 99 maxima, check engine light came on today. Took to auto-zone, codes
> read po325- knock sensor, and po303- number 3 cylinder misfire. Where
[quoted text clipped - 3 lines]
> wondering if I could replace knock sensor to save a little labor cost.
> Thanks for any help and info.

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