MrSmitty556 Posted July 8, 2021 Share Posted July 8, 2021 I've done some searching and can't really find a direct answer to this... I have a 2009 Legacy 2.5i that has had a flashing/solid TPMS light for a couple years now. Last year I had the sensors scanned and found a dead one. Replaced it and the light stayed off for a couple days then came back on. Figured more were dead so I would just replace them all when I did the tires again. Fast forward to last week. Replaced all four sensors with brand new Subaru units. They programmed fine but the light came back on after about 10 minutes of driving. Now its doing the typical 'flash when I start the car then go solid' every time again. All sensors scanned fine, reprogrammed them again and got the same thing. I figured it has to be a bad TPMS control module. I bought one off of eBay to try, part number 28201AG06A. I can't find much info on swapping this unit out. I know that its under the drivers seat but I've read about the modules in other models being tied into other systems and causing issues when they're unplugged. I've also read about issues with the weight/airbag sensors in the seat needing re-calibrated when the seat is removed. Does anyone have any info on what I might be getting myself into if I pull that seat and swap that module? Thanks in advance. Link to comment Share on other sites More sharing options...
boxkita Posted July 8, 2021 Share Posted July 8, 2021 usually a dealer swap thing, because reprogramming. are you sure the ebay one is good? Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
All_talk Posted July 8, 2021 Share Posted July 8, 2021 In my '07 Spec B I have swapped the control unit for another out of a '07 Spec B, one matching one set of tires, and the other matching a second set of tires. No issues. And you can do it with completely removing the seat, I just unbolted the seat and lean it back, I think there was one wire connector I disconnected because the lead was short. Also, I have removed and replaced the seat without issues with the airbag system, I think the key is to disconnect the battery before starting the work and getting everything back as it was before repowering. Link to comment Share on other sites More sharing options...
MrSmitty556 Posted July 8, 2021 Author Share Posted July 8, 2021 usually a dealer swap thing, because reprogramming. are you sure the ebay one is good? I think the eBay one is good, for $30 I figured it was worth a shot. Seller said it was working fine... In my '07 Spec B I have swapped the control unit for another out of a '07 Spec B, one matching one set of tires, and the other matching a second set of tires. No issues... I've read about people doing this to solve the winter tire light issue so I was hoping the swap would be easy. Good to know about the seat too, I'll take a look under there and see how easy it is to get too. Thanks for the replies. Link to comment Share on other sites More sharing options...
MrSmitty556 Posted July 9, 2021 Author Share Posted July 9, 2021 Update: Swapped the box out this morning, no problems. I didn't realize it was under the carpet, that almost threw me for a loop. I was planning on putting a new battery in the car anyway so I did the swap while the battery was out. I reprogrammed the sensors in but I'm still having the same issue. I know that the sensors are good, the tool can see them no problem and everything checks out. Both control modules being bad seems pretty slim to me. At this point I don't know what the issue could be. Looks like its electrical tape on the gauge cluster to get rid of the light... Link to comment Share on other sites More sharing options...
All_talk Posted July 10, 2021 Share Posted July 10, 2021 I know the light flashing every so often means the receiver is not a signal, I believe it will do this if just 1 or all 4 not sending. The solid on light means it’s getting 1 or more low pressure signals. What is the light sequence in your case? Link to comment Share on other sites More sharing options...
MrSmitty556 Posted July 18, 2021 Author Share Posted July 18, 2021 I know the light flashing every so often means the receiver is not a signal, I believe it will do this if just 1 or all 4 not sending. The solid on light means it’s getting 1 or more low pressure signals. What is the light sequence in your case? Flashing then solid. I scanned it and the ECU says it can't see any of the four sensors. All of them are good. I've tried clearing it out, relearning all of the sensors. The light will start flashing then go solid 10 minutes into a drive. After that it will flash and go solid every time I start it up. I've tried that other module, same thing. Link to comment Share on other sites More sharing options...
DaveWaters Posted July 18, 2021 Share Posted July 18, 2021 Do you have any LED lights on the car (even including dome light)? Or any other aftermarket devices that could cause radio interference? Link to comment Share on other sites More sharing options...
Max Capacity Posted July 18, 2021 Share Posted July 18, 2021 Here's my fix, put a piece of black electrical tape over the light on the dash. Mine has been on for years. Just after having new tires put on, the light came on. Found out two of the sensors had dead batteries. They are still dead, the cars doesn't care. IMO, stop wasting money on something you don't need. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
08SpecB_DE Posted July 19, 2021 Share Posted July 19, 2021 Did you program the sensor ID's to the module? It might be worth checking the fuses. Link to comment Share on other sites More sharing options...
theflystyle Posted July 23, 2021 Share Posted July 23, 2021 Do you have any LED lights on the car (even including dome light)? Or any other aftermarket devices that could cause radio interference? Thats an interesting idea. Have you encountered it yourself? Link to comment Share on other sites More sharing options...
DaveWaters Posted July 23, 2021 Share Posted July 23, 2021 No, I personally haven’t. I just recall reading about LED lighting interfering with other car electronics. So did a google and it seems like it could be a possibility. Link to comment Share on other sites More sharing options...
MrSmitty556 Posted July 27, 2021 Author Share Posted July 27, 2021 I did program the sensors into the car. It'll last about ten minutes each time I do this, then it's back to the flashing then solid light. No LEDs on the car either, everything is stock. I have about $50 tied up into this, I don't feel too bad about it. Bugs me that I can't figure it out but it may be the old electrical tape trick... Link to comment Share on other sites More sharing options...
apexi Posted July 28, 2021 Share Posted July 28, 2021 What subaru sensor part numbers? Could check for powers and grounds at the module. Link to comment Share on other sites More sharing options...
dgoodhue Posted July 28, 2021 Share Posted July 28, 2021 I had TPMS sensor that I can read on my 2009 Outback but the signal was too weak and it cause my TPMS to flash. Eventually the battery died 6 months later and I can not longer read it. At the age of 4th Gen, its only matter of time before all the TPMS sensor need to be replaced. Link to comment Share on other sites More sharing options...
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