Just bought an 09 Forester. The tire pressure dash light is on. I pumped up the tires to spec, including the spare, but light fails to go out. How should I proceed to fix?

most likely one or more of the sensors are bad or damaged if airing the tires to spec does not correct the issue.

Not really sure how that system works, tbh, so how to fix? i dunno

I believe you need to drive a mile or two for the system to reset itself.  And, of course, one of the sensor's battery may be dead as well.

 

Good luck,

3 hours ago, Rooster2 said:

Just bought an 09 Forester. The tire pressure dash light is on. I pumped up the tires to spec, including the spare, but light fails to go out. How should I proceed to fix?

1. Replace transponder in the offending tire - battery is dead.  It's 13 years old - not a surprise the batteries are dying. 

2. Car is new to you - so the possibility exists that the previous owner installed a different wheel(s) with different, unmarried sensors.  If that was the case then they simply need married to the car - Subaru does it for like $60 - $120 to reprogram all of them. 

Do you know enough about this car to discern if one of those is more likely that the other?

But for that much money, on a new to you car, and unknown sensors/batteries that are likely to fail in the near future - you might be better served replacing them all and reprogramming them to your vehicle. 

With a little effort you can find amazon sensors for much cheaper than the $$$ original Subaru units.  They're longevity probably won't be 10 years though - so you might want Subaru if you're the type of person who can't stand a light on the dash and plans to keep the car 10+ years. 

3 hours ago, Rooster2 said:

Just bought an 09 Forester. The tire pressure dash light is on. I pumped up the tires to spec, including the spare, but light fails to go out. How should I proceed to fix?

1. how low was the pressure? 
2. have you followed up after some time to check the pressure in case there's a leak?
3. how long have you driven since pumping up the tires?

My first post was assuming you've checked the tires and given it plenty of driving time to reset....

maybe drive to a Discount Tire, they may be able touse a gadget and 'interrogate' the system, diagnose the issue and/or re-marry transponders, etc.

7 hours ago, 1 Lucky Texan said:

maybe drive to a Discount Tire, they may be able touse a gadget and 'interrogate' the system, diagnose the issue and/or re-marry transponders, etc.

Yes, this - they can tell which (or how many) sensor it is. 

Ideally they don’t charge for diagnosis and eventual repair.  If so I’d rather hand them sensors and pay once to have it done...but that’s only viable if you know it’s a bad sensor for sure. Which has always been the case on known vehicles I’m working on.  Drive fine for years then light comes on...been a sensor every time. 

Edited March 12, 20215 yr by idosubaru

16 minutes ago, idosubaru said:

Yes, this - they can tell which (or how many) sensor it is. 

Ideally they don’t charge for diagnosis and eventual repair.  If so I’d rather hand them sensors and pay once to have it done...but that’s only viable if you know it’s a bad sensor for sure. Which has always been the case on known vehicles I’m working on.  Drive fine for years then light comes on...been a sensor every time. 

this is good to know, the other half's 06 Outback has those sensors

 

Thanks for all the info about sensors. Prolly more trouble and cost then it is worth to get sensor(s) replaced. Just better to keep an eye on tires to visually see when a tire looks low on air. Car is going to need new tires in near future, will see what tire store says about the sensors.

Thanks to all for your replies.