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2020 Forester
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Discussion Starter · #1 ·
Just purchased new Blizzaks on dedicated rims from Tire Rack with TPMS sensors installed at Tire Rack on 2020 Forester Sport. Used Autel TS508 to complete OBD relearn. Software on TS508 updated. I completed OBD relearn but after driving TPMS error light goes on after 10 minutes with no tire pressure readings. The tire sensors check out fine with the tool and I have no problem triggering them. Any ideas?
 

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2019 Forester Limited CVT
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192 Posts
Were they set to the correct frequency? I believe they changed from 315Mhz to 433 Mhz in MY 2019.
My cloned sensors work occasionally, but just show no reading, don't get a warning light.
 

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2018 Forester Limited
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If the OP was able to trigger and read the 4 sensors with his Autel TS508 set correctly to Subaru Forester option 1 (thru 2020 433mhz) and he was able to collect an output, so it sounds like TireRack installed the correct sensors.

When you did the upload, the Autel went thru the verification step and returned no DTC's (error codes)?

You rechecked the sensors, and they were OK.

Something I have not tried, but my ATEQ tool supported (and I assume the Autel does too) - recheck the OBD port for any new error codes or hex ID mismatches. I don't have time today, but see if there are any youtube guides on how to do diagnostics. I think "Advanced Mode" includes diagnostics?

Or, just try the whole wheel collection and upload again. Maybe something fouled on the first attempt.

EDIT: Oooh, just had another thought! The act of pinging the sensors should be all that is required for a full wake-up and initialization. But, you never know.... Try out the ring magnet in the kit.
 

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2018 Forester Limited
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You may need dealer help at this point. SSM or the equivalent to query deeper in and see if the code are resident in the TPMS processor and if the system is actually 'hearing' the sensor broadcasts. I don't know any other home remedy beyond what I've suggested.
 

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2020 Forester
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Discussion Starter · #8 ·
You may need dealer help at this point. SSM or the equivalent to query deeper in and see if the code are resident in the TPMS processor and if the system is actually 'hearing' the sensor broadcasts. I don't know any other home remedy beyond what I've suggested.
Yes. Thank you for your help. I have a email out to Autel as I bet there is a software issue. I will give the dealer a ring to see if they will give up any useful information. Here is the DTC that occurs after the sensors are not found.

543153
 

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2018 Forester Limited
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I went to the Service Manual that I have for my SJ (2018), and the highest chassis DTC listed is C2521, so a C2921 is something new for 2019+.

I checked into other SOA documentation, and got a "hit" with Subaru Tech Tips, April 2020 edition. Not good. A 3 page deep tech description of getting C2121 thru C2124 (you got 2 of 4), followed by C2921. It's a communications error, sometimes caused by a registration error (uploading the hex ID of the new sensors), or the system not seeing certain expected changes in broadcast data from the sensors (like incremental increase in temp or pressure as you drive indicating "live" data) over time. It might be an attempt to ensure real live data, and maybe not 'spoofed' or canned data?

You might have received bad sensors. There have been several threads on the Outback board about bad OEM sensors on 2020 vehicles, so if TireRack is still installing Schrader sensors, you might have joined a problem in progress.
 

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2020 Forester Touring CVT7
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I went to the Service Manual that I have for my SJ (2018), and the highest chassis DTC listed is C2521, so a C2921 is something new for 2019+.

I checked into other SOA documentation, and got a "hit" with Subaru Tech Tips, April 2020 edition. Not good. A 3 page deep tech description of getting C2121 thru C2124 (you got 2 of 4), followed by C2921. It's a communications error, sometimes caused by a registration error (uploading the hex ID of the new sensors), or the system not seeing certain expected changes in broadcast data from the sensors (like incremental increase in temp or pressure as you drive indicating "live" data) over time. It might be an attempt to ensure real live data, and maybe not 'spoofed' or canned data?

You might have received bad sensors. There have been several threads on the Outback board about bad OEM sensors on 2020 vehicles, so if TireRack is still installing Schrader sensors, you might have joined a problem in progress.
i just look at my copy of SI forester 2019 and the highest code I see is DTC C2821 WHEEL POSITION SENSING ABNORMAL
C2921 is not in the list at all

is it working if you install your old tires(sensors) ?

also check to see if your front sensors have different ID

C2121 FL TRANSMITTER NO DATA
C2122 FR TRANSMITTER NO DATA
C2123 RR TRANSMITTER NO DATA
C2124 RL TRANSMITTER NO DATA
 

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2020 Forester Touring CVT7
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if its from Tire Rack with TPMS sensors it is likely Autel sensors too , you can try cloning sensors ID from your original tires to your new one
 

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2020 Forester Touring CVT7
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also if you think it due to profile on your TS508 , you can try using 2019 Ascent ...
i used Ascent profile on my TS508 for Forester many times before they updated /added 2019+Forester

P.S. looing at Autel Forester profile it's not looking right to me , it is showing (FM5/PF3) , i always used Ascent HR3 just like Crosstrek HR3
i don't think I ever used actual Forester profile
 

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2018 Forester Limited
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The 5th generation Forester is the SK? Is there another designation for it? Please define FM5, PF3, HR3?

EDIT:
According to GoAuto web site, the SH (2008 to 2012) Forester was known internally as the PF3
 

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2020 Forester
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Discussion Starter · #14 ·
i just look at my copy of SI forester 2019 and the highest code I see is DTC C2821 WHEEL POSITION SENSING ABNORMAL
C2921 is not in the list at all

is it working if you install your old tires(sensors) ?

also check to see if your front sensors have different ID

C2121 FL TRANSMITTER NO DATA
C2122 FR TRANSMITTER NO DATA
C2123 RR TRANSMITTER NO DATA
C2124 RL TRANSMITTER NO DATA
Have not reinstalled old tires. I am holding out hope that software issue can be resolved.
 

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2020 Forester
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Discussion Starter · #15 ·
also if you think it due to profile on your TS508 , you can try using 2019 Ascent ...
i used Ascent profile on my TS508 for Forester many times before they updated /added 2019+Forester

P.S. looing at Autel Forester profile it's not looking right to me , it is showing (FM5/PF3) , i always used Ascent HR3 just like Crosstrek HR3
i don't think I ever used actual Forester profile
I will try the 2019 Ascent profile. Sensors installed at Tire Rack are Schrader brand. thanks
 

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2020 Forester Touring CVT7
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Tried the 2019 Ascent profile...no dice. Called Autel and they are sending to engineering review. Stay tuned...
you can roll old set next to the car program old set back in , turn ignition off and on , instead of driving the car you can use tool to trigger sensors (scan all 4 ) and the car will start displaying them ...
 

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2020 Forester Touring CVT7
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also take a picture of all new sensor ID's in your tool , just to see if ID look odd

here is from my forester
543317


543318


i did not drive or start a car for about 3 days , but after reading sensors with a tool it displays in the car ...
543319
 

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2018 Forester Limited
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you can roll old set next to the car program old set back in , turn ignition off and on , instead of driving the car you can use tool to trigger sensors (scan all 4 ) and the car will start displaying them ...
That's a good trick for diagnostics!
 

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2020 Forester
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Discussion Starter · #20 ·
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