Check engine light on for many miles, showed EGR error and knock sensor error. Replaced egr valve vacuum hoses, check engine light off. Knock sensor error still showing. Heard it was a glitch in the internal monitors but cannot find info on this. Do you know where I can locate that?

Code P0327 indicates that the readings from the #1 Knock Sensor circuit are too low, is outside of its operational window and malfunctioning. Symptoms

• Check Engine Light will illuminate
• Engine pings on accelration
• Engine may be running hotter or colder than normal
• In rare cases, the engine may not exhibit noticeable symptoms

Common Problems That Trigger the P0327 Code

• Defective Knock Sensor
• Defective Knock Sensor Circuit or connections
• Defective EGR System
• Malfunctioning Cooling System
• Rich air/fuel ratio

Common Misdiagnosis

• Knock Sensor replaced when cause of code P0327 was a cooling system problem
• Knock Sensor replaced when cause of code P0327 was an EGR system malfunction

ECU controls the EGR system. Check for vacuum to the valve with the engine running. There should be no vacuum. If you have vacuum disconnect the electrical to the vacuum control solenoid and see if the vacuum goes away. If it does you have a command or wiring problem and will need to trace the signal wire back to the ECU.

P0406 indicates high voltage on the EGR sensor circuit. this is recommended for every 30,000 miles be inspected. although EGR system do not requires periodic inspection. instead, check only if engine trouble's develop. most EGR's requires replacing EGR valve, cleaning passages and installing new vacuum hose. misrouted vacuum hose causes engine poor operation. so. not just to unplug it.

Technical Description

Knock Sensor Circuit Malfunction
What does that mean?

A knock sensor tells the engine computer when one or more of your engine's cylinders are "knocking", that is, exploding the air/fuel mixture in a way that delivers less power and can be damaging to the engine if prolonged. The computer uses this information to tune the engine so that it doesn't knock. If your knock sensor wasn't operating properly, so that it was always indicating a knock, the engine computer's response may have been to change the ignition timing on your engine. Knock sensors generally bolt into or thread into the engine block. This P0325 code may show up intermittently or the Service Engine light may be lit constantly. Other knock sensor related DTC codes include P0330.
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You may notice drivability problems including a lack of power and perhaps some hesitation. There may also be other symptoms.
Causes

A code P0325 most likely means one or more of the following has happened:

• The knock sensor is faulty and needs to be replaced
• There is a wiring short/fault in the knock sensor circuit

Possible Solutions

• Check the resistance of the knock sensor (compare it to factory specs)
• Check for broken/frayed wires leading to the sensor
• Replace the knock sensor

Sources: W. Farmer - Nissan

P0400 - Exhaust Gas Recirculation Flow Malfunction OBD-II Trouble Code Technical Description

Exhaust Gas Recirculation Flow Malfunction
What does that mean?

The exhaust gas recirculation (EGR) valve is vacuum controlled valve that regulates the amount of exhaust gases that re-enter the cylinders. The powertrain control module (PCM) determines how much based on engine load, temp, and other conditions. If the PCM detects that the amount of exhaust gases entering the cylinder were insufficient or non-existent, this code is set.
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No symptoms will likely be noticed by the driver other than the MIL (malfunction indicator lamp). However, non visible symptoms will be increased combustion temperature and increased Nox emissions.
Causes

A code P0400 may mean that one or more of the following has happened:

• Plugged EGR passage which restricts the flow of exhaust gasses
• Faulty EGR solenoid
• Faulty EGR solenoid wiring/harness
• Vacuum lines damaged/disconnected to the EGR valve solenoid or to the EGR valve
• Faulty EGR valve

Possible Solutions

Since EGR valve designs are different, no one test will suffice:

• Using a scan tool, operate the EGR valve with the engine running. If the engine stumbles, the problem was likely intermittent wiring problem or intermittent blockage problem
• If engine doesn't stumble, operate the EGR valve manually, if possible. If engine doesn't stumble and die, the ports are likely plugged. Removal of valve and cleaning of all ports will be required
• Checking of solenoid can only usually be done with a scan tool, because most solenoids operate with a duty cycle of voltage, rather than constant voltage
• Check all vacuum lines, hoses, etc for any damage
• Visually inspect the solenoid harness and the solenoid for damage
• Replace EGR valve

DTC P0332 is for a knock sensor, not egr valve. That's not to say one of the multiple codes you've mentioned wasn't for the egr valve.

What are some of the characteristics the vehicle is showing. By the way, what is the vehicle? In one place it says 1995 contour, in another it says 1995 explorer.

Hello,
The EGR solenoid is activated by the ECM at mid range speeds so if you are testing it at a idle it will not show voltage. The ECM grounds the solenoid to turn it on which supplies vacuum the source to the EGR valve.. To test the EGR solenoid unplug it and supply power to the terminals on the solenoid with jumper wires. Just apply power momentarily and listen for the click.Don't power it on for long as it will damage the solenoid if energized for long periods.If the solenoid is working check the EGR valve by connecting a piece of vacuum hose to it and applying vacuum to it. If you put your fingers under the edge of it you can feel the diaphragm moving as it opens and closes when applying and removing the vacuum. If don't have a vacuum pump tester you can do it easily with your mouth on the hose as it doesn't take much vacuum.If the EGR is stuck remove it and try cleaning the carbon out.If you can't free it up replace the EGR valve. If you need more help here is a site which provides diagnostic help with pictures.The also have the part availible for purchase at a very low price along with many more hard to find emission related parts. www.qualityresale.net

P0410 is a code for the EGR Valve. This can be checked by pulling vacuum on the hose attached to it while the engine is running. If the engine struggles when you do, it is working fine. P0327 is a fault on the Knock sensor. More precisely, a low voltage on the Knock Sensor. This is more than likely a severed wire or faulty sensor. I would recommend taking care of the EGR code and see if that cures both issues.

The knock sensor NEVER causes a drivability problem. DO NOT change it. Instead, clean the MAF, Mass Air Flow sesnor that's on the air intake tube near air cleaner. It is coated with varnish. Spray with carb cleaner several times and gently, gently brush the wires. Theya re glass coated. Be careful.

Then disconnect battery for 2 hours and then reconnect and drive for 0 miles for computer to relearn engine contrils.

Also go here for more help
http://groups.yahoo.com/group/villagerquest/

What i did is remove the check engine bulb coz even if you change the knock sensor the light will still go on coz our engine is a bit old.

Hi

The EGR valve allows a percentage of exhaust gas back into the engine during part throttle driving conditions. The exhaust gas enters the combustion process and cools the charge down slightly which lowers the emissions.

The EGR flow malfunction is usually rectified by removing the EGR valve and cleaning out the valve itself and the port(s) on the intake where it was sat, which have probably become narrowed due to all the deposits. You need to use a piece of wire to get right into the ports and clean them right out. The valve is connected to both the intake manifold and the exhaust, it is round and will have a vacuum pipe to it. It will either be mounted directly on the intake manifold, or linked to it via a hose, probably metal, and it will be linked to the exhaust via a hose, probably metal.

The knock sensor listens for engine knock, usually caused by incomplete combustion or over advanced ignition timing, and retards the ignition timing to counteract the knock.

You very highly likely have a faulty sensor, but check the wiring first. To suss the problem properly you would need to have alive scan carried out.

Knock sensors are usually located under the intake manifold on these cars and are a complete pain to get to. You'll probably need a universal joint type of affair to get it off. They held on with one bolt.

Very best regards

Geordie