My girlfriend has an 01 Impala that just keeps costing me. Ive fixed several things and worked my way around others. The LOW TIRE PRESURE light keeps coming on even though there are pretty good tires all the way around, none low on air. What triggers this light and can i bypass it or fix it? Also this car grumbles loud as hell from the motor. Is this normal for these things? Its got 104,*** miles on it and it's a 3.4 liter 6 cyl. I believe..... Thanks for any info.

For the engine noise, all I can tell you is that you must locate the source of the noise. You probably have a bad bearing, worn out alternator, or something similar. You should try removing the serpentine belt and start the engine to see if the noise is still there. If it is, then there is something wrong internally like a timing chain or something. If the noise is gone, then you need to inspect all the pullies that are driven by the serpentine belt including alternator, power steering, A/C, idler pulley, tensioner pully, etc.

The tire pressure monitor system (TPMS) can be pretty picky.

1. Check all of your tire sizes to make sure they are all the same size. I have seen many problems with people putting used tires on the vehicles that don't match the other tires in size. I have also seen this caused by tires that are the same numerical size but one is new and the rest are worn-out causing a difference in the circumference of the tire. This makes the tires rotate at different speeds and makes the TPMS "think" there is a low tire.

2. the tire pressures need to be checked with a GAUGE. You could have one or more tires OVER INFLATED and this will also cause the light to come on. I have seen lots of problems with people that keep adding air to the tires, but don't ever use a gauge (they just use the "eyeball gauge"). This does not work with a TPMS. They ALL need to be inflated to the pressure that is on the lable inside the drivers door. They also must all be within 2 Psi of each other.

NOTE: After adjusting tire pressures, it can take up to 30 minutes of straight line driving to get the light to go out. Do not expect it to go out right away, it is not going to happen unless you reset the TPMS with a scan tool.

If you are certain that the problem is not being caused by tire sizes or tire pressures, then the TPMS should be scanned to check for fault codes. There could be several other reasons why the light could keep coming on (bad wheel sensor, communications faults, internal TPMS module failure, etc.)

This car does not have tire pressure sensors it reads off of wheel speed sensors thru abs. so as stated already all tires have to be same size and correct pressure. with this done will need to reset the monitor. as of now i do not have info in front of me but you can do it yourself look in owners manual it will tell you how. i f i remember correctly you go thru radio to reset oil life and tire monitor. and drive 15 minutes and horn will sound will look it up monday and post for you if you dont find it first.

If al ltires are set to the correct pressure, then one or more Tire Pressure Sensors are not reporting the pressure. Th ebest thing to do is have it fixed correctly. Most tire stores are equipped to find and replace the bad sensor. You really are better to fix it, because if a tire is run low or flat it will be ruined before you realize it. As for the grumble I assume it does it at idle, not moving? if so take the drive belt off and see if the noise goes away. if it does spin each pulley and see if any fell rough, like the tensioner and water pump.