2012 Camry. The display inside the car shows the 4 tires with PSI number each tire icon. I have tested this 4 times myself. One of the numbers keeps dropping, dropping, etc. But if I check/put nitrogen in the tires, it goes back to proper reading. Then with time, that number will go down, down. Any idea what needs to be replaced? Thanks.

 

This may be a clue. I was driving down interstate, and a loud hissing sound came from back right for like a few minutes. I looked around back seat area and saw nothing strange. I thought maybe fire extinguisher in trunk was activated, but I check it and it was OK.

 

The tire pressure sensors are inside the tires. One for each tire.

Given what you describe the tire with the dropping pressure could have a leak. The tire could have picked up a nail, etc and has a slow leak.

Have a tire shop check the tires for leaks, nails, etc.

If the problem is more then a simple patch they are warranted by the tire manufacturer. This info is in the car warranty literature.

The tire sensor system is warranted by Toyota.

Also check the spare tire if you think the noise is in the trunk.

 

Thank you Toyomoho. Indeed the air in the tires is usually around 34. When the display in the car shows otherwise, I check the tires and they are all still around 34. Today they said they checked for leaks, nails, etc.

I've studied more and learned about TPMS sensors which should be able to read ??? from the control center ?? or something like that. I talked to guy from Bartec and he said to go by somewhere that uses their unit and have them do a quick scan and it should point to the specific problem. So already after the shop today, when I got home it has already started coming down...it was like 28....I KNOW it will go down more each day, but the actual pressure in the tire is OK....

I could not get the service manager's interest in testing further. I did read that the 2012 Camry has come out with some new type of ??? and that the Bartec site shows there is a video or something to LEARN about the new sensors onthe 2012 Camry. I looked at the tool for the camry and it was like $1600.

Also the dealer really did me wrong when I purchased the car. One time the tires were to be rotated, but they had put a plug in the back right tire, and when I looked that tire was still on back right. I called them on that one, and they redid the rotation, but the manager DID NOT want to give me paperwork cause it would go to ??? and ???? and questions would be asked....SO WHAT..... and now this, and the same service manager.....

So possibly the spare tire could have made a spewing type noise, such as a can coke was shook up and then opened and it was spewing....give me a little more lead on this and I'll check the tire however recommended.

Thank you very much for your input as I'm having to do this research myself without their help...

 

To recap your statements:

If air is added to the tires the indicated pressures on the dash will read correctly for over time then the pressure indication for one tire will drop to 28 psi.

Yet the actual tire pressure in all tires is 34 psi, not 28.

There was a spewing noise front area cause unknown.

A few thoughts.

The tire pressure monitoring system is called TPMS.

If the actual tire pressure of all 4 tires is not dropping (stays at 34 psi) then the tires do not have a leak.

I don't know if the spare tire is monitored by the system or just the 4 tires mounted on the car. Check owners manual for this info. If the spare tire is monitored check the spare tire pressure and make sure it correct.

If one of the mounted tires was making a spewing noise it would most likely have lost air and have lower actual pressure.

The odds of new spare tire having such a leak it could be heard outside the trunk is nil but check the spare tire pressure anyway.

The cars fuel tank evaporation emissions system components (EVAP) is located under the cars chassis in front of the fuel tank. The tank is located in back of the gas cap area. Unlike fuel tanks of many years ago the fuel tank on this car is not vented at atmosphere via the gas cap and is a closed system.

The EVAP system is designed to prevent gasoline vapors from being venting into the air. It does this by capturing the vapors and storing them in a charcoal canister to be eventually routed to the engine air intake system then burned in the engine.

In order to prevent fuel tank damage the EVAP system has a pressure relief valve on top of the fuel tank which will open if the fuel tank air pressure becomes to high. This valve bleeds the excess pressure in the tank off to the atmosphere. Suppose the spewing noise could be this valve venting.

When you fill the fuel tank was gas, are you cutting off the fuel fill when the nozzle automatically turns off or trying to get as much fuel into the tank as possible? The tank is designed with enough air space to allow for pressure changes but if overfilled with fuel this air space will be smaller.

As to the tires, my guess is the problem is with one of the tire sensors. Each tire has a sensor mounted inside the tire. The tire sensor system is warrantied byToyota and the dealer should investigate this under warranty.

The federal government mandated this system be installed in newer cars for safety reasons and as such it should be working as designed for safety.

I suggest you start keeping a written record of actual tire pressures versus indicated tire pressure over a period of time including any pressure drops. As in date of tire pressures both actual and indicated along with date of check.

Once you have this record go to the dealer and show them explaining the one tires actual pressure is XX but the indicator pressure for the tire is showing less at YY. AND this low pressure indication happened over time, dropping from the higher pressure.

Yet the actual tire pressure has remained constant at XX (I assume the actual tire pressure is remaining constant or at least all 4 tires are maintaining the same pressure and one is not lowering in pressure).

If this is the case I highly suspect one of the tire pressure sensors has a problem (defective). The dealer should be able to use their diagnostic tools which are like the Bartec design but custom designed for Toyota to find the tire sensor that is reading low.

Then replace the sensor. This requires demounted the tire, replacing the sensor and remounting.

In closing.

The spewing noise may be unrelated to the tire pressure problem but something else. But check the spare. If the pressure is OK the tire does not have a leak.

The problem with the tire indicator system appears to be the tire sensor. This sensor is covered under the Toyota warranty and the dealer should fix it.

The federal government having mandated this system be installed in newer cars thinks the system is important for safety and as such you think is needs to work correctly. Try to get the safety angle across to the dealer to help motivate them to investigate and fix the problem.

If the dealer refuses to do anything try another dealer as not all operate the same way. Or talk to the dealer general manager or even owner.

Some dealers do not like to perform warranty work at they make less profit or just break even.

If you have exhausted getting dealers to help the owners manual has number you can call for Toyota customer support to open a case on this problem. Your position would be the tire pressure system has the problem you describe. Attempts at having a dealer investigate have been unproductive, the system is indicating an inaccurate pressure which is safely problem and you want it fixed under warranty.

Try to get a dealer to fix the problem as if you go over their heads they may no longer want to help. Unfortunately Toyota exercises little control over their dealers in motivating them to help with customers problems. But don't let this stop you from pursuing the getting help from Toyota customer service.

Some states also have binding arbitration on warranty issues via a third party as why to work out issues. But work with dealers fix.

 

How low does the pressure reading can go? If it goes down to zero and your tire is still 34 measured by mechanical pressure gauge, the problem is the sensor. If you may, try to deflate the tire down to zero and compare to the dash reading.