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2000-2005 Discuss your 2000-2005 Bonneville SE, SLE, and SSEi Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 12-09-2015, 08:48 PM   #1
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Default P0446 - Fixed It

Wife was given a 2000 Bonneville SSEI from the in-laws for my oldest daughter to learn how to drive and take to college. 86K in okay condition.

Replaced all rotors and pads - no issues.

Chased around a P0446 code for a week and finally fixed it today.

1. Replaced gas cap - code came back
2. Replaced Vent valve - $30 - code came back
3. Took off canister - holds pressure and no obstructions
4. Checked hoses - all seem good
5. Replaced purge valve - $35 - code came back
6. Replaced FTP (fuel tank pressure sensor) - $40 - NO MORE CODE...

About 2 hours of labor to change out everything and $100 in parts....kind of happy but pleased to have done this by searching a bit on this forum...thanks to all!!!

NOW I HAVE TO FIGURE OUT WHY THIS CAR STARTED TO DIE ON ME INTERMITTENTLY SINCE I HAD THE REAR END JACKED UP THIS WEEK. Did this twice since......if car idling it may stall or going down the road coasting it may stall....only twice. Have a feeling something gunked up fuel lines and the fuel filter looks like it is stock with 86K and 16 years...very rusty.
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Old 12-10-2015, 02:18 PM   #2
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Glad you found the issue, and thanks for sharing what you did to fix it.

If the fuel filter is that old I'd replace it first, use some PB Blaster Penetrating spray on it and let it soak in for a while, the respray it and see if it will come lose, of course make sure you relieve the fuel pressure first, you don't want a face full of gas!
If it still has issues after that check for fuel pressure, if pressure is up to spec it would not hurt to add a can of Seafoam, and a bottle of Heet to a full tank, I recently got some bad gas that started causing misfires in my #2 cylinder, after running both through it for a while the issue cleared up.
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Old 12-11-2015, 10:57 AM   #3
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When it dies does it sputter or lose power and die, or does it die like you flipped a switch? Does it re-start first try, or does it take a few tries? If it won't start, check to see if you have spark at any one of the plugs. If you don't have spark it could be the crankshaft position sensor. If you do have spark, check fuel pressure. The fuel pump could be failing. Both of these failures are very common on the Bonneville.
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Old 12-11-2015, 11:33 AM   #4
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Well, after the dirigible cycles a new code popped up this morning P0442 - well, I've replaced everything but the canister (just because it isn't blocked and I can blow through every orafice (closing off the other 2) and the pressure holds. I haven't replaced the lines though.

Not sure where to begin, again! I guess a smoke test would help at this point.
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Old 12-11-2015, 02:59 PM   #5
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A smoke test would help, there are some videos for a DIY smoke test on youtube, if you have one done pay attention to the intake manifold area as well.
Also as for the soft EVAP hoses, most are on the front of the motor area, the throttle body, purge valve, canister, etc..
If you grab any and get black stuff on your hands I'd go ahead and replace them, the hose is cheap at most auto parts stores.
You should have a little bit of soft EVAP hose in the rear up under the car, around the fuel filter and gas tank area, if you find any I'd just go ahead and replace it all, as it is already 15 years old.
The same goes for the soft EVAP hose rubber connectors, you should have a few under the hood, if you remove them all to take in to the auto parts store to get replacements, I'd take a few pics of the areas they came from, so there is no confusion when putting them back.
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Old 12-11-2015, 06:25 PM   #6
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My neighbor put the smoke machine to the car and no leaks? He tried smoking from the purge valve back and from the gas tank filler forward...nothing, no leaks.????

Later, I ran a quick scan and received a P0452.....now I'm wondering if that was the code I had this morning, not P0442???? Arggg

I just replaced the darn FTP sensor before all this happened, right before I fixed the P0446 code.

Any advice on the P0452?
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Old 12-11-2015, 06:41 PM   #7
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https://www.gmforum.com/obd-ii-troub.../p0452-284203/

Maybe there was a voltage issue with the FTP wiring.
I'd find a wiring diagram, and see where the wires from the FTP go to if the voltage is reading low, then ohm test each wire form end to end to see if there are any shorts in it..

From that post above, just going to post the whole post from the above link.

"" P0452

Description
FUEL TANK PRESSURE SENSOR LOW VOLTAGE


PCM monitors fuel tank pressure sensor signal to detect
vacuum decay and excess vacuum during the enhanced EVAP diagnostic.
Fuel tank pressure sensor measures the difference between air pressure
(or vacuum) in the tank and the outside air pressure. PCM applies 5-
volt reference and ground to the sensor. Sensor will return a signal
voltage between 0.1-4.9 volts. If PCM detects a fuel tank pressure
sensor signal that is excessively low, DTC will set.

Symptoms
You likely won't notice any drivability problems.

Causes

Fuel tank pressure sensor signal is less than 0.1 volt.

Solutions

Check for poor terminal connections at fuel tank pressure
sensor connector.
Check for shorts.
Check for damaged harness.
Replace fuel tank pressure sensor.

""
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Old 12-12-2015, 01:20 PM   #8
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Quote:
Originally Posted by 2kg4u View Post
When it dies does it sputter or lose power and die, or does it die like you flipped a switch? Does it re-start first try, or does it take a few tries? If it won't start, check to see if you have spark at any one of the plugs. If you don't have spark it could be the crankshaft position sensor. If you do have spark, check fuel pressure. The fuel pump could be failing. Both of these failures are very common on the Bonneville.
Thanks! It dies like you flipped a switch! Restart takes a little coaxing....feathering in accelerator.....
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Old 12-12-2015, 01:22 PM   #9
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Interesting, last night after a cold brew, I went and unplugged for sensor.....then plugged back in. Put key in on position and ran a quick scan and the p0452 code wasn't there??? I didn't clear the code? Can a code erase itself?
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Old 12-12-2015, 02:16 PM   #10
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Yes, codes can clear themselves out after certain drive cycles, key on'* or self tests are done. It depends on the device and the software.
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