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SES light will not turn off, codes P0440, P0446

Tiny
YOURMINKY
  • MEMBER
  • 1997 NISSAN SENTRA
  • 1.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 115,000 MILES
The SES (service engine soon) yellow light came on. Local auto stores will not erase the code due to EPA restrictions but they told me the error codes are P0440, P0446.
Auto forums recommended removing rust around the gas cap and get a new gas cap. I removed all the rust, got a new gas cap, but the SES light never went away on its own. People are saying that I have to disconnect the battery to erase the code. I did that, I left the negative battery terminal unscrewed over night, touched the unplugged negative wire with the positive wire for a few seconds to drain all capacitor charges, but the error code is still there, SES light remains lit.
Read in another forum how to reset ECU in cabin without battery disconnect. Below is the method:

1) Put the car in "on" mode, do not start.
2) At the third second (three dings) after turning to "on" (again not started) position, Floor (all the way down) and release the accelerator pedal fully five times in less than five seconds.
3) With the gas pedal at release position, wait about seven seconds, then floor the accelerator pedal and hold for ten or more seconds. Hold pedal down until the SES check engine light will start to blink slowly (my SES light never blinks).
4) Release the pedal and floor it down once again and hold for ten seconds. After these ten seconds the check engine light will begin to flash much more rapidly (My SES light never blinks). Release the pedal after fifteen seconds or done flashing rapidly. Turn the car off wait for a few seconds and then back on. The ECU/ECM is now reset.

Please help.
This is an ongoing thing for me. The rust around the gas cap comes back every year and I have to scrape it off. I need a way to be able to clear the SES light every year when it comes back during the rainy season. The "in-cabin pressing accelerator pedal method" worked for me a few years ago. I can no longer remember the timing sequence for pressing the pedal. None of the YouTube videos are for my model. If you have done this for my car model and cleared the SES light, please let me know the pedal pressing sequence.
Also, where is the fuse/circuit breaker located for the ECU/ECM unit?
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Sunday, April 15th, 2018 AT 1:10 PM

11 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hello,
I have never heard of the gas pedal clearing. Here is a guide to help you clear the codes:

https://www.2carpros.com/articles/check-engine-light-clear-codes

But I would check the charcoal canister and the vapor lines for cracks this is probably your problem.

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken
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Monday, April 16th, 2018 AT 2:24 PM
Tiny
YOURMINKY
  • MEMBER
  • 106 POSTS
Thanks for the reply. The pedal method actually worked for me in the past. I forgot the sequence. It is about timing. I am doing it wrong. This problem comes back every year when the rust comes back at the gas cap. I am used to it.
By the way, do you know why the code will not clear after disconnecting the battery overnight?
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Monday, April 16th, 2018 AT 3:24 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
The code will not clear because one, it is stored in memory and two, you have not repaired the problem and the codes simply resets. You have a code for a vent solenoid. Have you tried changing it? The code is not going to go away if the problem is not resolved.
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Monday, April 16th, 2018 AT 4:18 PM
Tiny
YOURMINKY
  • MEMBER
  • 106 POSTS
That is not my experience so far. This is the fourth time I got this code over last ten years. It is gas cap rust related. Do you know the the exact gas pedal timing sequence? As I mentioned, the pedal sequence works when done properly until the rust comes back.
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Tuesday, April 17th, 2018 AT 12:32 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Okay, first, there is no gas pedal method to clear codes in this vehicle. Second, P0446 has nothing at all to do with a gas cap. It is an electrical circuit code for the vent control solenoid circuit so you can change the whole gas tank if you choose and still not repair this code. It could be a wiring issue but 99% of the time it is just a bad vent valve solenoid.
The p0440 is just a generic code caused by the P0446. Fix that and they both disappear.

From the service manual:

How to erase DTC (No Tools)
1. If the ignition switch stays "ON" after repair work, be sure to turn ignition switch "OFF" once. Wait at least five seconds and then turn it "ON" again.
2. Change the diagnostic test mode from Mode II to Mode I by turning the mode selector on the ECM.
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Tuesday, April 17th, 2018 AT 1:29 PM
Tiny
YOURMINKY
  • MEMBER
  • 106 POSTS
Is there a way to test the solenoid circuit?
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Tuesday, April 17th, 2018 AT 1:58 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Sure, but you would need a bidirectional scan tool to energize the solenoid and understand how to read and test an electrical circuit.
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Tuesday, April 17th, 2018 AT 2:04 PM
Tiny
YOURMINKY
  • MEMBER
  • 106 POSTS
Please let me know where is this solenoid located and what should I be looking for. I have plenty of experience with electronics.
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Thursday, April 19th, 2018 AT 9:55 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
The vent valve is attached to the charcoal canister under the car, near the fuel tank. See image.

To test the circuit use a bidirectional scan tool to activate the valve and then test for power and ground arriving at the valve plug. If you have both power and ground, replace the valve.

I also suggest that you use and LED test light when doing this and not an incandescent bulb type as the current required to light the bulb can damage the PCM.
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Friday, April 20th, 2018 AT 3:59 AM
Tiny
YOURMINKY
  • MEMBER
  • 106 POSTS
The code was erased three days ago. The gas cap rust was polished out. So far no SES light.
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Friday, April 20th, 2018 AT 11:31 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Sweet! Please let us know if it goes back on.
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Saturday, April 21st, 2018 AT 12:23 PM

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