Pontiac MAF EVAP and Throttle Codes in Computer

'07 Pontiac G5. 2.2L Ecotec.

Question: Check engine light codes came out as P0446(Evaporative Emission (EVAP) Vent System Performance), P0121(Throttle Position (TP) Sensor Performance) and P0102 (Mass Air Flow (MAF) Sensor Circuit Low Frequency) - mechanic cannot get the throttle body, dealer cannot get throttle body.

Is it worth it to only replace 2 out of the 3 parts? Should i wait for the throttle body to be in stock? If dealership cannot get the part, what are the odds of the part ever being available? Is the throttle body something that can be purchased online somewhere?

Tech Reply: The EVAP code is not related to the other codes. The other 2 may be related. But may not be a bad part. Is the car running bad or hard to start? Do you have a sunroof?

Reply: It's not hard to start but it is having some RPM issues. When the car accelerates, the RPMs shoot up and appear to be delayed before they drop back down, as if the gears are not shifting as quickly as they should. the car is also eating a lot of gas. Yes i have a sun roof but it hasn't been open in almost a year(since last summer). I've spoken to other mechanics who say the throttle body/sensor should not need to be replaced-that if i replace the EVAP Canister and MAF sensor that it should solve the problem.

Answer: The EVAP canister vent solenoid would have nothing to do with the way it runs or using gas, unless the canister is full of gas. This is not very common. The vent valve sticking and causing a code is very common. The MAF sensor code could be caused by the throttle body, as well as the other symptoms. A few things- have seen several wiring problems at the Mass airflow connector. Pull on each wire to see if one breaks. This would cause your RPM problems. Also, have had sunroof drains in the driver side leak water into the car and corrode a main connector. Open the drivers side door and remove the plastic panel on the side of the dash. Disconnect the connector behind that panel and look for green or wet electrical terminals.

Reply: So if i replaced the MAF, that should eliminate my RPM problem? But what about the throttle body? I was told the TPS is within the throttle body for my car and the whole body needs to be replaced, but no one's told me why, and no one can seem to find the part for my car. Even the dealer didn't have it in stock nor could they tell me when they would get it. Is this necessary to replace?

Answer: The MAF sensor would not be the problem with the RPM, but a connector problem could. The TPS is in the throttle body, and could also be most of your problems. Without seeing the car for myself and looking at data, i could not say for sure. Look at those wiring problems i described first. Getting the throttle body from the dealer is hard because we are out of stock on them right now. It would need to be ordered and when it is available, you would get it.

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