# BPT functioning properly?



## mtnsmith (Oct 27, 2010)

I have a '98 4-cyl with a P0400 code and cleaned and tested the EGR valve and related components. One of them being the BPT and I was wondering if it should free flow from the center port that comes from the back of the egr valve or if there is something wrong with this? I went to clean the port out with some throttle body cleaner and it came out the ports that go to the egr valve and egr solenoid. I am not fimiliar enough with this part to know how it should work and I don't want to just throw parts at the truck. Thanks!


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## philritzert (Aug 20, 2010)

Testing procedure for BPT Valve:
Plug one port on top of the valve. Apply vacuum to the other port. Vacuum should not hold. Apply pressure to the bottom port and vacuum should hold across the top.

It sounds normal for the fluid to escape the valve when you spray into one of the top ports. Without pressure on the bottom port however, it should not go through the top ports. 

Be careful what chemicals you use on these valves. The diaphragms are sensitive and can dry out and break easily.

Also, its common for the tube to the BPT to become clogged. The metal tubes can be cleaned with more harsh chemicals. (I used acetone on mine and it took only seconds to relieve a completely carbon-clogged tube). The intake passages also become clogged with carbon deposits and this can set the code. Remove the EGR valve and check the valve, passages, and tubes for clogging. Check all vacuum hoses and replace as necessary.


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## azrocketman (Oct 5, 2005)

mtnsmith said:


> I have a '98 4-cyl with a P0400 code and cleaned and tested the EGR valve and related components. One of them being the BPT and I was wondering if it should free flow from the center port that comes from the back of the egr valve or if there is something wrong with this? I went to clean the port out with some throttle body cleaner and it came out the ports that go to the egr valve and egr solenoid. I am not fimiliar enough with this part to know how it should work and I don't want to just throw parts at the truck. Thanks!


You might want to look at this technical service bulletin:

NTB05-040a

1998 - 2000 FRONTIER & XTERRA WITH KA24 ENGINE;
MIL WITH DTC P0400, P0402, ROUGH IDLE, DRIVABILITY
INCIDENTS, DIFFICULTY PASSING I/M TEST FOR NOX

APPLIED VEHICLES: 1998 – 2000 Frontier (D22) with KA24 engine
2000 Xterra (WD22) with KA24 engine
APPLIED ENGINE: KA24DE 4 cylinder engine
IF YOU CONFIRM:
• DTC P0400 (EGR) or P0402 (EGRC-BPT Valve) is stored in the ECM,
and/or
• The vehicle exhibits rough running or other drivability incidents,
and/or
• Difficulty in setting the EGR System Readiness Test (SRT) status to CMPLT.
and/or
• The vehicle does not pass inspection/maintenance (I/M) emissions (smog) test for NOx.
ACTION:
Clean the intake manifold EGR ports.

Steve


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## mtnsmith (Oct 27, 2010)

Awesome, thanks for the pointers. So since air/cleaner will free flow from the bottom port out the top ports, the BPT is bad? That appears to be what I get from the first response. I did not use compressed air or excessive pressure in the bottom port to discover this. 

Thanks for the TSB also, are the intake egr ports the 4 plugs between the throttle body and main section of the intake? I inspected two of them this weekend when I checked the egr passages and they all appeared clear. 

Thanks Again!


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## azrocketman (Oct 5, 2005)

There are four allen screw plugs in the top of the intake manifold. Remove those plugs for access to the EGR ports.

Steve


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## brownsfan3785 (Mar 23, 2015)

azrocketman said:


> There are four allen screw plugs in the top of the intake manifold. Remove those plugs for access to the EGR ports.
> 
> Steve


I know this is an old post, but i need help with this issue as well.
I've got a 2001 Altima, 231k miles, runs great but the P0402 is getting to me as well.
I had a tech tell me my EGR ports could be partially blocked which results in the exessive flow to the others.

Car runs great out of the garage when motor is cold. After it warms up, i get a slight hesitation when i accelerate slowly from a stop. 1100 RPM @ 15-20 MPH and i can feel a small shake thru the gas pedal. Give it more gas and it goes away.

Does this sound like P0402? Sometimes I get P0303 along with it. CEL comes and goes. Gas mileage was crappy all winter long too.
I hope somebody can help.
Is it possible to clean this out without pulling the intake manifold off?


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## azrocketman (Oct 5, 2005)

The ports could be cleaned on my Frontier without removing the manifold. I'm not sure about the Altimas. You may want to look at the service bulletin I referenced above.

Steve


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