No power at high RPM's, code P0138

Tiny
CMAYEUX
  • MEMBER
  • 2000 NISSAN MAXIMA
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 119,000 MILES
My car for some reason seems to have very little or no power at all when the rpm's get above 3,500. It screams all the way to 6,000 rpm's but the entire time it goes through that range the car doesn't seem to go faster at all. When you get on it from a complete stop it will put your head back and you can feel its power but if you are just cruising and then floor it, it will drop down a gear but does not seem to go any faster. Sometimes it also shifts gears extremely hard. Also the service engine soon light stays on and I have plugged a code reader into it that says P0138- o2 sensor ckt slow response (bank 1, sensor 2) and P0138- o2 sensor circuit high volts (bank 1, sensor 2) From my own research people with similar issues with this car have suggesting cleaning and/or replacing the mass air flow sensor and that replacing the o2 sensors did not solve the problem.
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Monday, July 27th, 2009 AT 1:14 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The code you have pertains to the heated oxygen sensor (sensor 2) which is post cat. What I suspect may be happening is the vehicle isn't controlling the air fuel mixture properly which can cause a power loss.

There are a few things that can cause this code to present itself. For example, a harness or connector issue, the sensor circuit is shorted or open, the sensor is bad, fuel pressure, injector issues, even intake engine vacuum leaks.

If you look at the attached directions and pics, I provided the diagnostics for this issue. To determine the cause, this is what will need performed.

___________________________________

Diagnostic Procedure
Diagnostic Procedure Step 1
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Diagnostic Procedure Step 2
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Diagnostic Procedure Step 3
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Diagnostic Procedure Step 4
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Diagnostic Procedure Step 5
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Diagnostic Procedure Step 6
pic 6

Diagnostic Procedure Step 7
pic 7

Diagnostic Procedure Step 8
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Diagnostic Procedure Step 9
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Diagnostic Procedure Step 10
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Diagnostic Procedure Step 11
pic 11

______________________________

Let me know if this helps or if you have other questions.

Take care,
Joe
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Monday, August 24th, 2020 AT 6:39 PM
Tiny
CMAYEUX
  • MEMBER
Many thanks Joe. I will pass this to the workshop.

I am still waiting for them to give me a list of checks already made.

Cheers,

Roger Hart
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Tuesday, August 25th, 2020 AT 12:53 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

You are very welcome. If you have a chance, let me know what they tell you. I'm interested in knowing.

Take care,
Joe
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Tuesday, August 25th, 2020 AT 8:07 PM
Tiny
ROJAR
  • MEMBER
Hi Joe

Nissan have just resolved this fault. It turned out to be the Swirl Control Valve which was defective. They left it disconnected and the car is fine now.
Cheers,
Roger Hart
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Tuesday, September 29th, 2020 AT 5:57 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

I'm glad to hear they found it, Also, thanks for letting me know.

Please feel free to come back anytime in the future if you have questions.

Joe
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Tuesday, September 29th, 2020 AT 7:19 PM

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