The dash indicators on my 99 show tire pressures about 3 to 4 lbs lower than readings taken at the tires with a hand held guage. This happens on all four tires. Does this mean that my sensor batteries are failing or is it a calibration issue that can be corrected?

Comments solicited.

 

I'm going to bet on the sensors (the '99 sensor batteries are near or past their end of life depending on mileage and use) but here's how I would go about it. First I'd confirm the tire pressure with a different hand held gauge. Ok, I understand you probably have a pretty decent gauge but this is a process of elimination. If a second known good gauge confirms the first pressure readings then you know it is either the calibration or sensors themselves. (of course if a second good gauge doesn't read exactly what the first did, then go find a 3rd or 4th good gauge until two gauges match) There are plenty of threads on here that detail the tire learning procedure and I beleive it's in the owner's manual as well. Shouldn't be a problem to find it. There isn't anything else you can do with the existing sensors so if the recalibration still shows a difference between car and hand helds then you know the problem lies with the sensors. JMO, I'd live with it knowing there's 3 or 4 lb difference and keep an eye on them and wait until the sensors start to fail. I'd be concerned if the difference changes from say 3-4 lbs to 5-6-7 lbs. It won't be long after the first sensor fails that you'll see the second go. If you are meticulous about your car's tire wear then don't wait and just replace the sensors before the batteries fail. Then it's either new sensors or refurbished. I'd also be concerned if I was going to refurbish my own or buy refurbished that there wasn't a 'electro-mechanical' problem of the sensors reading the correct tire pressure. In other words, buy new. Good luck.

 

I agree. Either batteries in them are dying or your manual guage is wrong. I use a digital tire pressure guage and its surprisingly close to the TPS sensors.

 

Good tips - Thanks.
I've been using the slip stick type air guage. I'll try again with a dial type.

 

My digital (Radio Shack) is right on with my TPM's, my manual dial type gauge reads 2 lbs lower.

 

I was just thinking about what you replied and have an observation. Isn't it funny, and we all do it. We assume the $50,000 car is wrong but the $3 tire gauge is right.

Point being, who knows, maybe the hand held is wrong and the $50k car is right this time.

 

I've got two Corvettes...'99 and the '07 which both of course have the TPMS. Both read very accurate when compared to two different digital tire pressure guages. I would say all 8 wheels are within 0.5psi of the three different measurements....TPMS and two different digital gauges.

 

I suppose it's just suspicion of electronics vs an extremely simple mechanical device......

 

Your display readings are reasonable. TPMS sensors were not designed to be "test gauge accurate". Their function is only to alert the driver if a major loss of tire pressure has occurred.

 

I am betting your stick type gauge is off since all sensors are uniformly different from it.