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FIXITMAN
FIXITMAN, Master Technician
Category: Buick
Satisfied Customers: 17143
Experience:  ASE MASTER CERTIFIED, AA DEGREE AUTO/DIESEL TECH
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Codes p0449 and p0452 on my 04 rendezvous Roy, several weeks

Customer Question

Codes p0449 and p0452 on my 04 rendezvous
Roy, several weeks ago you suggested I change the vent valve solenoid to correct these conditions. Did that today... I started the car several times and the code had gone away. Once I put the car in gear the codes were back. Erased several times but they're back on every start now. Wanted to know if you had any other suggestion.
Thanks,Tom
Submitted: 6 months ago.
Category: Buick
Expert:  FIXITMAN replied 6 months ago.

Hello Tom, my name is***** you tell me how the vehicle is running besides the light coming on?

Customer: replied 6 months ago.
Hi Bobby,
The car seems to run fine. Starts well... accelerates well... I need to get it to pass emissions here in NJ and that 'CEL' is an automatic fail.
Tom
Expert:  FIXITMAN replied 6 months ago.

In the underhood fuse box check fuse 24 for the vent valve. If it is fine then the issue is more than likely in the fuel tank pressure sensor.

Customer: replied 6 months ago.
Hi Bobby,That fuse had blown.. so I replaced it. Erased the codes. Started it up. No codes. Then I took it for a*****to the store and when I was done shopping and started it back up the codes were back. Drove home and checked the fuse and it was in good shape... was kind of hoping it was blown ... at least that would have narrowed it down some.Just FYI... when I first contacted you there was also a code P0128.. had to do with the coolant level. That code is now gone. Didn't think it was relevant so I did not mention it?So you think it's the fuel tank pressure sensor? Where is that? Is it a DIY kinda thing?Thanks,Tom
Expert:  FIXITMAN replied 6 months ago.

I am not sure it this sensor is the issue. The fact that the fuse was blown tells me that it may be something else. Let me check the wiring schematic and get back with you in a few.

Customer: replied 6 months ago.
TY
Expert:  FIXITMAN replied 6 months ago.

Do you happen to have a voltage meter to run some tests on the circuit?

Customer: replied 6 months ago.
I do. I have an older power probe to trace lines as well. Need to have an idea which wires to follow. Thanks.
Expert:  FIXITMAN replied 6 months ago.

Thanks. We need to first start by testing the voltage at that fuse with the key on in the run position. It should have battery voltage. If not let me know. If it does then with the key still on I need to know if that voltage is at the connector at the vent valve.

Customer: replied 6 months ago.
OK.. I'lll try this Saturday morning...
Expert:  FIXITMAN replied 6 months ago.

Sounds good. Let me know what you find and we can continue from there.

Customer: replied 6 months ago.
Update: Before I even started trying this I had a problem. The car won't start. I'm almost positive I could a hear a humming sound from the fuel pump last week and this week I hear nothing. The car cranks fine but never starts.Checked the battery voltage with the key in the 'On' position... it's about 11.5V At the fuse its about 11.25V. Haven't dropped the tank to check the vent valve yet. The fuse for the Vent Valve is still in good shape.Tom
Expert:  FIXITMAN replied 6 months ago.

Does the check engine light come on when the key is turned on? Is the security light on when cranking the engine?

Customer: replied 6 months ago.
Check engine light DOES come on with key 'on'. Security light DOES NOT come on while cranking. It almost started tonight.
Expert:  FIXITMAN replied 6 months ago.

Thank you. It sounds like you have a voltage problem. I would check the voltage at the IGN fuses under the hood. Are you still not hearing the fuel pump when the key is on?

Customer: replied 6 months ago.
Still don't hear the fuel pump.First I'm going to put a charger on the battery (overnight) and see if it takes. From what I've read, 11.5V might mean the battery is damaged or done. It seems like a good place to start.Thanks
Tom
Customer: replied 6 months ago.
The battery took the charge and the car started right up this morning... that's all I had time for. I'm gonna look at the voltage after work and see if it holds the charge. I'll update later on.
Expert:  FIXITMAN replied 6 months ago.
Sounds good. Thanks for the update.
Customer: replied 6 months ago.
Battery voltage was low again. I'm going to test the alternator as well... but the battery is most likely done. I'll update when I have something further

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