Andre 3000

I checked my engine light code and I got 0304, knock sensor. What do I have to do and what kind of problems can this cause? Since yesterday my car has started shaking occassionally under any kind of acceleration. It shakes as if it is running out of gas, if anybody knows what i'm talking about. But there's plenty of gas. I wonder if my tranny is locking up on me??? Help

Daniel B. Martin

Diagnostic Trouble Code 0304 points to a problem with the Knock Sensor. The KS is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is senses as vibrational pressure. This pressure is converted into a voltage signal and sent to the Engine Control Module (The computer).

This malfunction is detected when an excessively high or low voltage from the KS is entered to the ECM. Possible causes include...
- the harness or connector (The KS circuit is open or shorted).
- the KS

The KS may be checked with an ohmmeter.

1) Raise the hood. View the engine from the driver's fender. Look into
the deep valley between the cylinder banks and below the intake manifold.
Identify the KS as a black item fastened to the block by a single vertical
bolt. A wire harness wrapped in black leads toward you, out of the valley.
That is the KS sub-harness.

2) Follow the KS sub-harness to it's nearest connector. This is connector F121.
It is located near the upper right-hand corner of the valve cover of the forward cylinder bank, as viewed from the front of the car.

3) Disconnect F121. You have to do a "press the latch and wiggle and
pull" to disconnect it. F121 has only two pins; if you see more than two
pins, you have the wrong connector. Use a digital ohmmeter capable of
measuring more than 10 Megohms. You want to measure the pins of F121, not
the sockets of the matching connector. Measure the resistance between a
good ground (such as the battery negative terminal) and pin #2 of connector
F121. On my car this is the highest of the two pins, the one closest to
the front of the car. The factory spec is 500 - 620 Kohms.

The manual says you have to remove the intake manifold to replace the KS. However, I think that a person with good dexterity and a 10mm ratcheting box wrench could replace the KS without disturbing the manifold.

Daniel B. Martin

Your symptoms are more likely to be from an engine problem than a transmission problem. I suggest you reset the Engine Control Module and drive normally. If the Check Engine Light returns do another readout of Diagnostic Trouble Codes. Perhaps this time you will get more than one Code and the combination of codes will be helpful.

Shaking under acceleration could be caused by a misfire in one cylinder. This could be the result of a bad ...
- fuel injector
- ignition coil
- spark plug

maxi-milliyon

I'm the master of the 0304 knock sensor code. That K.S. costed me $160 from the dealer. Get it changed as soon as you can. My O2 sensor went bad because the K.S. retardes the timing and makes the car run rich. So in other word it tells the ECU do dump more gas. This causes TTTTEEEEERRRRRIIIIBBBBBLLLLEEEE gas milage, and the performance will be lacking. Thanks Danny B. for the help.
My mechanic didn't have to take off the intake man. either. No trouble with it ever since, by the grace of GOD.
Holla!

Maxi-milliyon

Sprint

iTrader: (10)

Please tell me you are only using 93 Octane in your car

Daniel B. Martin

I'm glad your car was fixed, but someone has given you bad information. In response to signals from the Knock Sensor, the Engine Control Module does retard the timing but this has no connection with fuel mixture. Did your mechanic replace only the KS or were other repairs done at the same time?

Andre 3000

I only use 93 octane, the best for the best. I can't check out my car today cuz it's raining like a hurrican e down here. I'll check that out asap. but where do i get an ohmmeter. I reset my ecu yesterday when i checked the code, and the light hasn't come back on yet. I only drove for like 20 minutes today.

Andre 3000

I just drove some more and the last wasnt come on yet. My car is starting to shake even when I'm sitting at a red light...WHAT DO I DO???

gabuchu

Sounds like a misfire. Take out all 6 spark plugs and exam it. Check for oil, gasoline, or one that looks different than the others.

Daniel B. Martin

Let's work on the premise that the shaking is due to a misfire. If the misfire were due to a bad ignition coil you should have a Check Engine Light and a Diagnostic Trouble Code in the 0603-0608 range. You don't have this DTC so the misfire is most likely coming from a bad fuel injector. There are two tests the home mechanic can make, the sound test and the resistance test.

Sound test...
This test is performed with the engine idling. Use a mechanic's
stethoscope or a length of rubber vacuum hose, and listen to each injector.
All injectors should sound alike. If you find one which makes a different
sound (or no sound at all) you have found a problem.

Resistance test...
This test is performed with the engine off. Use an ohmmeter to measure the
resistance of each injector. This does not require removing the injectors.
I don't know the correct resistance value for the injectors on your model,
but they are typically a low number such as 16 ohms. The important thing
is they should all be equal. If you find one injector with substantially
higher resistance than the others, it is bad. If you find one with zero
ohms (short circuit) that is truly unfortunate, because the injector is bad
and it may also have damaged the Engine Control Module (the computer)
because of excessive current drain.

Measuring the resistance of the front bank of cylinders is easy because the
injectors are in plain view. Disconnect the injector electrical connector
for cylinder #2, measure the resistance, reconnect the connector. Repeat
for the cylinders #4 and #6.

Measuring the resistance of the rear bank of cylinders is almost as easy,
but it is difficult to reach the injectors. The resistance may be measured
at a conveniently located electrical connector. Notice the largest,
thickest electrical harness at the top of the engine. This is the Engine
Control Harness and it is shaped like a U, with the open top of the U at the
driver's side of the car. The U has two corners. Look at the corner
nearest the passenger seat. Just inside that corner you will find an 8-pin
electrical connector. This is connector F131. Disconnect this
connector. Now look at the male part, the connector half with the pins
exposed. They are arranged in two rows of four pins.
The pins are numbered 1 - 4 (top row) and 5 - 8 (bottom row).
Measure the resistance of:
- injector #1 between pins 1 and 2.
- injector #3 between pins 1 and 6.
- injector #5 between pins 1 and 5.
Be sure to measure the PINS, not the female receptacles.

The dealer's shop is equipped with high-tech diagnostic instruments. These are wonderful devices but they are expensive and the dealer has to recover his cost by charging you for diagnostic time. Sometimes the home mechanic can do legitimate diagnostic work with nothing more than a ohmmeter and a rubber tube.

Andre 3000

Where are my injectors??

Daniel B. Martin

Please don't read this as a smartass answer because it isn't meant that way. If you don't know where your fuel injectors are, then you shouldn't attempt your own diagnosis and repair. Please seek a professional service provider.

Ask around your town. Ask friends, neighbors, coworkers. Chances are you will hear some horror stories, and also some glowing recommendations.

Independents usually charge less than the dealer. Perhaps you will find a former Nissan dealer technician who opened his own repair shop. That's a good man to know!

Andre 3000

I might be able to do it if i know where they are. I won't try it if i can't tho. Can you tell me where they are?

Daniel B. Martin

Please get a Haynes repair manual. You can buy this book at any large bookstore or auto parts store. It may be available at your public library. Refer to Haynes, page 4-9. It has a detailed explanation and good photos.

Andre 3000

Thank you very much Daniel B. I'll let you know what happens.

AntGVR4

Question: did you check the KS before you replaced it? By this i mean did you or your mechanic check the resistance reading of the KS to check if it is in spec ?

Reason is i have a KS code but following Daniel B. Martin's instructions i measured a resistance from the KS that was correct. This is why i have not changed it. Althought at this point i think i am just going to change it and see what happens.

Ant

maxi-milliyon

Danny B, My car was give off a code for the knock sensor and a code for the rear O2 senser.My mechanic changed both at the same time. Please explain how someone has giving me wrong info.
Holla
Maxi-milliyon

Daniel B. Martin

Your previous post said the K.S. retardes the timing and makes the car run rich.

... the K.S. retardes the timing ... True.


... and makes the car run rich. False.

AntGVR4

Sorry for the repost but i need this info

Maxi-millyon:
Question: did you check the KS before you replaced it? By this i mean did you or your mechanic check the resistance reading of the KS to check if it is in spec ?

Reason is i have a KS code but following Daniel B. Martin's instructions i measured a resistance from the KS that was correct. This is why i have not changed it. Although at this point i think i am just going to change it and see what happens.

Ant

Daniel B. Martin

The resistance test I posted is a valid test but not a complete test. If your Knock Sensor fails the resistance test it is definitely bad. However, if the KS passes this test that does not mean it is definitely good. We should also remember that the Diagnostic Trouble Code points to a problem with the KS or its connector and harness. It does no good to replace a KS if the problem is inside the harness.

Andre 3000

i got some new info

my check engine light finally came back on

0104...0304...0504

what now?

Daniel B. Martin

Diagnostic Trouble Code 0104 points to a problem with the Vehicle Speed Sensor or the associated wiring.

The Vehicle Speed Sensor installed on the transaxle. The part inside the transaxle has a plastic gear which is driven by the internal parts of the transaxle. The part outside is a signal generator which produces a square wave of amplitude 5.2 volts and frequency proportional to vehicle speed.

Remove the VSS, attach a voltmeter to the electric leads, and spin the gear
by hand. If you get zero volts, it's dead.

One owner discovered his VSS was not fully seated in the transaxle. He just tapped it inward, and retightened the 10mm mounting bolt.

For more information please refer to the Chilton repair manual (page 4-22) or the Haynes repair manual (page 6-16).

Daniel B. Martin

Diagnostic Trouble Code 0304 points to a problem with the Knock Sensor. The KS is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is senses as vibrational pressure. This pressure is converted into a voltage signal and sent to the Engine Control Module (The computer).

This malfunction is detected when an excessively high or low voltage from the KS is entered to the ECM. Possible causes include...
- the harness or connector (The KS circuit is open or shorted).
- the KS

The KS may be checked with an ohmmeter.

1) Raise the hood. View the engine from the driver's fender. Look into
the deep valley between the cylinder banks and below the intake manifold.
Identify the KS as a black item fastened to the block by a single vertical
bolt. A wire harness wrapped in black leads toward you, out of the valley.
That is the KS sub-harness.

2) Follow the KS sub-harness to it's nearest connector. This is connector F121.
It is located near the upper right-hand corner of the valve cover of the forward cylinder bank, as viewed from the front of the car.

3) Disconnect F121. You have to do a "press the latch and wiggle and
pull" to disconnect it. F121 has only two pins; if you see more than two
pins, you have the wrong connector. Use a digital ohmmeter capable of
measuring more than 10 Megohms. You want to measure the pins of F121, not
the sockets of the matching connector. Measure the resistance between a
good ground (such as the battery negative terminal) and pin #2 of connector
F121. On my car this is the highest of the two pins, the one closest to
the front of the car. The factory spec is 500 - 620 Kohms.

The manual says you have to remove the intake manifold to replace the KS. However, I think that a person with good dexterity and a 10mm ratcheting box wrench could replace the KS without disturbing the manifold.

Daniel B. Martin

Diagnostic Trouble Code 0504 points to a problem with the Automatic Transmission Communications line. Pulse signals are exchanged between the Engine Control Module and the Transmission Control Module to assure smooth shifting during hard acceleration or deceleration.

This malfunction is detected when the ECM continuously receives an incorrect voltage from the TCM. Possible causes include...
- Harness or connectors (The communications line circuit between the ECM and the TCM is open or shorted.)
- TCM
- Discharged or faulty battery

Andre 3000

0104
Vehicle Speed Sensor:
My speedometer has not been working for about 2 weeks and I could've figure out why. I'm planning on installing indiglo gauges next week when I receive them...do you know if it will work after I do this? What caused the problem?

Daniel B. Martin

Does the odometer work normally? If the Vehicle Speed Sensor is bad, it should not.

I don't know any reason why installing new gauges will help. Something is broken. You need to figure out what is broken and fix it.

We don't really know what is broken so it is risky to speculate on what caused the problem. Perhaps a Nissan engineer could put a failed part under a microscope and do a failure analysis. You and I don't have the equipment or skill to do this.

Andre 3000

The odometer doesn't work and my fuel gauge doesn't work either. I just put the import intelligence lay over gauges, so i thought it might just be a problem with the needles.

maxi-milliyon

Ant 95, My car gave off a code. I then had my mechanic check the harness with the meter. Then he check the K.S. itself and it was dead. He then changed and no problems ever since (by the grace of GOD). It also save me a lot of money in gas. Holla

Maxi-milliyon