EGR P0402 chat GPT

[VStar650CL]

They're a little different, I'd imagine slightly different response curves.

The 02E00 fits these:
1995-1999 200SX GA16DE, SR20DE
1980-1981 720 Pickup, L20B
1996-1997 Pathfinder, VG33E
1987-1990 Pulsar NX, CA18D
1991-1999 Sentra, GA16DE, J/GA16DE, J/SR20DE, SR20DE

The 10W00 fits these:
1989-1998 240SX, KA24D, KA24DE, KA24E
1984-1986 720 Pickup, Z20, Z24
1993-2001 Altima, KA24DE
1989-1994 Axxess, KA24E
1986-1994 D21, KA24E, VG30E, Z24
1995-1997 D21U, KA24E, VG30E
1993-1994 Maxima, VE30DE, VG30E
1987-1990 Pathfinder, VG30E, Z24I
1993-1995 Pathfinder, VG30E, Z24I
1993-1998 Quest VG30E
1990-1997 Stanza KA24DE, KA24E

You should be using the 10W00 in your SX. No, it isn't normal for it to fail every 2 years.

[mosilvia]

Thank you for your answers as always. What do you think causes the BPT valve to fail? From the looks of it, it doesn't seem like the sort of part that would break so easily.

[VStar650CL]

The biggest reason they fail is the same as that exhaust temp sensor, carbon buildup. Unfortunately, when the port plugs up, there's no good way to clean it out like you can clean out a manifold. Is something maybe making your ride run rich?

[mosilvia]

That exhaust temp sensor is Egr temp sensor?
Which port does it plug up?

Happy July 4 !!

[VStar650CL]

Yes, I was referring to EGR temp (which also carboned-up on you). I probably shouldn't have called it "exhaust temp" although that's what it measures indirectly. The BPT port to the exhaust responds to backpressure in order to meter the EGR flow, modulating vacuum to the EGR valve. It's actually a bleed, venting vacuum completely away from the EGR valve when backpressure is low (idle and low RPM), then gradually allowing more and more vacuum as RPM's rise. When the port clogs with carbon the diaphragm doesn't deflect as much as it should (or at all), causing the EGR to open less than it should (or not at all). The ECM detects that through the EGR temp and throws a P0402. The thing is, the port to the BPT is a dead end, so typically the only way it builds up a bunch of carbon is if the engine is chronically running rich.

[VStar650CL]

Oh, yah, happy Fourth to you and everybody!

[mosilvia]

You're talking about the port inside the BPT, right? Can't I just clean it with parts cleaner? I remember seeing that done on YouTube.

[VStar650CL]

You can try it, but I don't know if that will get crust off the exhaust side of the diaphragm and housing. Also, parts cleaners like Brakleen aren't particularly good at breaking down carbon. Intake cleaner is a better choice. Lastly, blow into the exhaust port and make sure nothing comes out of the vacuum ports. If it does, the diaphragm is leaking. That isn't fixable.

[mosilvia]

Thank you
I have lots of bpt valves
So I try cleaning

[VStar650CL]