Nissan Maxima 1998 P0325 P0400. Failed inspection.

Nissan Maxima P0325 P0400 error code. failed inspection. Please advice what service should I select when making a service purchase in yourmechanic.com
The problem seems to be Knock sensor replacement / Gas re-circulation…but don't see these services listed.

My car has 180000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
The code P0325 may set for a variety of reasons including: 1) that the knock sensor has failed; 2) there is an open or short in the wiring harness; or 3) the electrical connection (terminal) to the sensor is poor. Sometimes a failed ECU can set this code but that is rare. P0400 can set if: 1) the EGR valve is not opening due to no vacuum opening the valve from the EGR control solenoid or the EGR valve itself not holding vacuum; 2) The EGR temperature sensor is not registering a temperature change when the EGR valve is opened; or 3) The EGR passages are physically blocked, typically by carbon deposits, and thus is no or inadequate flow of exhaust gases into the intake manifold.

Codes provide clues as to what is wrong with a vehicle but an actual diagnostic has to be performed to conclusively and accurately identify the reason a code has set. In particular, almost all codes refer to, or involve, multiple possible causes and just because a "part" is referred to in a code does not mean that that part is faulty. To get a speedy resolution to your issues, the recommended service is a check engine light diagnostic. If you request that service, the responding certified mechanic will read the codes and then test actual parts, that is perform a diagnostic, to find the fault and get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

What the P0400 code means. P0400 is an OBD-II generic code that the engine control module (ECM) detected the engine exhaust gas recirculation (EGR) valve is not flowing recirculated exhaust gases when it is commanded to open the flow of gases into the intake manifold.
What Does the P0400 Code Mean? Diagnostic trouble code (DTC) P0400 code stands for “Exhaust Gas Recirculation (EGR) Flow Malfunction.” It is triggered when the flow of exhaust gas recirculation is lower than what the powertrain control module (PCM) expects.
The EGR valve is located in the engine compartment (underneath the hood). Most engines require exhaust gas recirculation to meet emissions standards. If the EGR valve has gone bad, the car will not pass emissions.
If the code P0400 is caused by some minor issue like a faulty EGR temperature sensor and the EGR system works properly, there should be no problem driving. However, if the EGR system doesn`t function properly, the combustion temperature will be higher, which in the long run could cause engine damage.
Spray the EGR valve cleaner onto the carbon deposits. Remove the carbon buildup with the use of a pipe cleaning brush and dull scraper. Repeat the entire process until all of the carbon deposits have been removed. Wipe off the surface using a clean piece of cloth.
The failures are usually caused by a build-up of deposits in the EGR valve over a period of time that causes them to stick. This build-up is part of the ordinary operation of the vehicle and should be regarded as a serviceable item requiring repair or replacement.
Moreover, many EGR problems can be avoided by simply ensuring that the vehicle is maintained regularly and gets a decent blat down a highway at least once a month, with plenty of accelerating and decelerating (pottering around town at low speeds is especially bad for EGR valves).
Technically you can drive without a working EGR valve.

It won`t affect the health of your engine, but it will hurt the environment. The role of your EGR valve is to reduce the number of toxic NOx gases in the air, so if it isn`t working quite right, more toxic gases will be released into the air.

EGR Fraction Based Control

Critical sensors are an exhaust manifold pressure sensor (P2), an intake manifold pressure sensor (P2) and a speed density estimate of total mass flow. Exhaust and intake manifold pressures are used to control the EGR valve and VGT vanes.

The EGR valve is the main component of the EGR system and it`s normally closed. It connects the exhaust manifold to the intake manifold and is controlled by either a vacuum or a built-in electric step motor.
Disadvantages of EGR Delete

Some diesel vehicles can experience adverse effects like reduced horsepower, increased exhaust gas temperature and engine knocking. In some cases, it can be more beneficial to have an EGR valve replaced, rather than bypassed.

EGR deleting is the most highly recommended solution. This is achieved by reprogramming the ECU to not use the EGR valve. This will result in cooler engine temperatures straight away, as well as improved throttle response and better fuel economy.
Car care experts recommend cleaning your car`s EGR valve after driving 45,000 to 50,000 miles to maintain it better.
You can try spraying an EGR cleaner into the valve while the engine is on and revving at 2000 RPMs. Don`t spray too much at one time, however. Allow the engine to recover between sprays. And wear gloves as well—the spray is meant to remove carbon particles, so imagine what it will do to your skin!
An EGR delete kit is an aftermarket performance part that removes the EGR valve and prevents exhaust from being redirected back to the engine. Ultimately, this allows your vehicle to function as if it never had an EGR valve. There are a number of key differences you`ll notice after having an EGR delete kit installed.
If your car is running poorly, you may be having problems with your exhaust gas recirculation valve, or EGR. While you can`t test your EGR valve function from home, you can clean it there, a simple task that effectively acts as a repair.
When an EGR valve fails, combustion temperatures rise, leading to hotter exhaust. These temperatures often end up literally melting the inside of your catalytic converter, leaving it incapable of cleaning your exhaust.
Valvoline EGR Cleaner is an effective cleaning spray used to dissolve deposits in the exhaust gas recirculation valve, air intake system, and inlet valves. It helps maximise engine efficiency, allowing it to run smoother and more optimally.
Provides immediate thorough cleaning of the air intake system, air flow sensor, inlet valves, turbo and EGR systems. Dissolves gum, lacquer, tar, carbon and deposits. Restores perfect air flow towards the combustion chamber.
Remove and clean any carbon buildup to the EGR Valve. Remove and clean any carbon buildup to the EGR temperature sensor. Removing carbon buildup/ partial blockages out of EGR tubes to the intake manifold. Replace defective EGR temperature sensor.
Mechanical EGR valve position sensors are mounted on the top of the EGR valve. EGR pressure sensors will be located close to the EGR valve as the exhaust gas hose must be connected to the sensor as well as the valve.
These common causes may include a clogged EGR valve that can no longer allow the correct flow of exhaust gasses, a faulty EGR valve due to the low vacuum coming from the EGR control solenoid, or an EGR that can not hold the vacuum.
What are the symptoms of a failing EGR valve? A faulty EGR valve can cause problems with the flow and operation of the EGR system leading to performance issues including a reduction in power, reduced acceleration and decreased fuel efficiency. It can also cause vehicle emissions to increase.
The failure of the EGR valve on the vehicle is not out of the ordinary, as this issue can arise on most modern diesel engines. The failures are usually caused by a build-up of deposits in the EGR valve over a period of time that causes them to stick.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Nissan Maxima 1998 P0325 P0400. Failed inspection.
ANSWER : The code P0325 may set for a variety of reasons including: 1) that the knock sensor has failed; 2) there is an open or short in the wiring harness; or 3) the electrical connection (terminal) to the sensor is poor. Sometimes a failed ECU can set this code but that is rare. P0400 can set if: 1) the EGR valve is not opening due to no vacuum opening the valve from the EGR control solenoid or the EGR valve itself not holding vacuum; 2) The EGR temperature sensor is not registering a temperature change when the EGR valve is opened; or 3) The EGR passages are physically blocked, typically by carbon deposits, and thus is no or inadequate flow of exhaust gases into the intake manifold.

Codes provide clues as to what is wrong with a vehicle but an actual diagnostic has to be performed to conclusively and accurately identify the reason a code has set. In particular, almost all codes refer to, or involve, multiple possible causes and just because a "part" is referred to in a code does not mean that that part is faulty. To get a speedy resolution to your issues, the recommended service is a check engine light diagnostic. If you request that service, the responding certified mechanic will read the codes and then test actual parts, that is perform a diagnostic, to find the fault and get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Why does the emission inspection failed almost every time its due for DMV inspection?
ANSWER : Hi there:

Honestly, the lack of consistent driving could be the reason why you have frequent emissions issues. If the car does not run frequently and have an opportunity to circulate built up carbon deposits on the inside of the fuel injection system or exhaust system, failed emissions testing may be the result. The best thing to do is to drive your vehicle once or twice per week about a month or so before your emissions testing is needed. Also, it’s a good idea to replace air filters frequently before emissions testing is completed. This article is a good one that helps many car owners learn what they can do to help improve emissions testing.

I was told that p1273 code for my 2004 Nissan maxima is gonna keep coming on until I get oxygen sensor from actual Nissan dealersh
ANSWER : Hi there. When it comes to replacing O2 sensors or any other sensor, it is always recommended to use an OEM or original equipment manufacturer replacement part. The sensor is designed to collect data and transmit it through an electrical harness and to the ECU to be stored. However, it is possible that the electrical harness itself is the reason why your receiving this error code (which is specific to Nissan vehicles). You might want to have a professional mobile mechanic come to your location to determine the right course of action by completing a check engine light inspection.

Where are the cam sensors located on 2009 Nissan Maxima vq35de engine? 2009 Nissan Maxima
ANSWER : Hello – the cam position sensors for this engine (2) are each located near the passenger side end of the cylinder head for each cylinder bank. The engine cover must be removed to access them, and the factory sensors have green plastic connectors, making them a bit easier to spot. For assistance, I recommend a camshaft position sensor replacement performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, replace these sensors, and get you back on your way.

Need to have transmission service on 2014 Nissan Sentra SV but would like to use only fluid manufactured by Nissan? How can I?
ANSWER : To answer your most important question first, you can absolutely specify that only genuine NIssan OEM dealer supplied transmission fluid (as well as any applicable filter) be used in your vehicle. Generally speaking, OEM parts are preferred and, in many cases, are the only way to avoid headaches. If you are providing the fluid, you can simply eliminate the "parts component" of the quote (there is a delete all parts option in the quote, leaving you only with labor charges). If you desire that YourMechanic procure the fluid, it might be easier to simply call in your service request and just make it clear on the phone that only OEM Nissan fluid is to be used. To obtain service, please call YourMechanic’s request for service line at 1-844-249-6752. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

210 gas mileage on a Nissan Maxima with a full tank of gas
ANSWER : Yes, change the fuel filter anyway. It’s so old so you might as well. But that gas mileage is pretty much normal for Maximas. Those have V6 engines that are very powerful. Most people drive them reasonably fast. The faster you drive a car, the higher your gas mileage is going to be. Be happy that the thing is still running and keep changing the oil filter. Watch the cooling system to make sure that it’s not overheating. If you maintain the car right, it should be able to last.

how do I replace a thermostat on a Nissan Maxima?
ANSWER : The thermostat is located on the front of the engine. The engine is mounted transversely so the front of the engine will be facing the passenger side and the thermostat in near the alternator. The battery must be disconnected and coolant must be drained first to prevent spilling coolant on electrical components and causing a short. From here, items can be removed until access to the thermostat is acquired. Consider hiring an experienced technician like one from YourMechanic who can come out and perform the thermostat replacement service for you at your leisure.

I have a 2006 nissan maxima that turns on but once I put it on drive, it’s drives for a bit then stops, no check engine light
ANSWER : This may be a sign of a faulty MAP sensor as the vehicle responds adversely to a load put on the motor (i.e. putting it in gear, turning on AC or engaging the brakes). The Manifold Absolute Pressure (MAP) sensor senses engine load and generates a signal that is proportional to the amount of vacuum in the intake manifold. The engine computer then uses this information to adjust ignition timing and fuel enrichment. When the engine is working hard, intake vacuum drops as the throttle opens wide. The engine takes in more air, which requires more fuel to keep the air/fuel ratio in balance. When the computer reads a heavy load signal from the MAP sensor, it adjusts the fuel mixture to slightly more rich than normal so the engine can produce more power. The computer will then retard (back off) ignition timing slightly to prevent detonation that can damage the engine and decrease performance. This may also be caused by other closely related components such as a dirty or failing mass air-flow sensor, a faulty throttle position sensor or potentially a vacuum leak. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.