2020 Nissan Altima - Engine problem. Lots of codes

NGINE MALFUNCTION POWER REDUCED SERVICE NOW, same thing came on about Just over 48k miles. Today’s date is June 8. I’ve parked the car and happened to be near an oil change place. It read a code of P0404. I will call Nissan when they open on Monday to ask about this. According to Google the code is possibly for a diagnotic trouble code DTC that indicates a problem with the Exhaust Gas Recirculation EGR circuit’s range or performance. It can appear on any vehicle with an OBD system including the 2019-2022 Nissan Altima L34 with a PR25DD engine.

As you’ve already discovered, p0404 indicates a problem w/the EGR function. It’s part of the emissions control system, specifically to reduce tailpipe nitrogen air-pollutants. This particular code is suggesting there’s some sort of problem with the electronic control or monitoring of the EGR function.

The basic EGR function is passive, no electronic control. The EGR valve opens a varying amount, controlled by a simple vacuum signal. The upside of the EGR being open is it reduces pollutants. The downside is it reduces engine power. A fully open EGR valve could stall the engine. A little may good, but a lot may be bad in other words. The electronic control is used to optimize the basic function. I have no experience w/you Altima’s EGR configuration, but on my Corolla’s (which is probably similar) there’s both an electronic actuator and a sensor. The actuator is used to provide a computer- override & completely disable the EGR in situations where it might stall the engine, like when stopped at a stoplight or there’s other stuff loading the engine; e.g. the A/C, alternator, radiator fans, etc. The sensor allows the computer to verify the EGR valve is actually open when it should be.

Most any good shop should be able to figure this out. They’ll connect their diagnostic scanner to your car’s computer and from that data will narrow down what’s causing the problem and allow a fix. If your engine is idling really poorly or badly misfiring, probably a good idea to have the car towed to a shop. Running a misfiring engine can damage other parts you definitely don’t want damaged, like the catalytic converter. Best of luck.

Your Nissan has a warranty on the powertrain (engine and transmission) for 5 years or 60K miles.

Take it to a Nissan dealer. Might cost you a diagnositic fee but the repairs could be free.


Unfortunately, the emission warranty for the EGR system is only 2 years/24,000 miles.



Darn, ain’t that a pi$$er!

No warranty!

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wow, that is pretty crappy warranty coverage by Nissan.

What do you mean?

All vehicles have the same emissions warranty.


On the positive side, the Altima’s EGR system worked fine for 4 years. That system is situated in a pretty tough environment, hot carbonized exhaust gasses flowing through on a daily basis and all. . It’s amazing it works at all. EGR problems are pretty common in many makes/models/years by reports here.

I don’t deal much with gassers, but the diesels I work on have a much better warranty coverage than that. Emissions stuff on my Duramax Chevy’s are like 8 years.
I’ve not heard of anything being only 24,000 miles before.

Who’s talkin’ about diesels?


oh, I thought you said “all vehicles”.

Oh, you did.

On the negative side it ONLY lasted 4 years. Many, many cars go many, many more years before having EGR problems.


30 year old Corolla, I’ve never had an EGR problem. But it is hard to tell whether the EGR system is working 100% correctly or not. About all I can say it is mostly working.

I have to monkey (mostly cleaning carbon deposits) w/my truck’s EGR system about every 3 years to keep it in top tune. But there’s never been any driveability symptoms when it isn’t working.

2 years/24,000 miles is the federal required minimum warranty coverage. Nissan and most other manufactures have a 3 year/36,000-mile basic vehicle warranty which covers engine and emission related parts.

Vehicles registered in California have a 3 year/50,000-miles warranty on emission related parts.

The EGR cooler on the 2.5 liter engine is covered by the “Long-Term Emission System Defects Warranty” for 7 years/70,000-miles.

There is an Engine Control Module software update for P0404 fault occurring in cold weather. Software updates are included in the Engine Control Module 8 year/80,000 Federal Emission long-term emissions warranty.