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I replaced my two rear tires yesterday on my 05 997 and took a short drive today. Less then a mile out the dash lit up with 3 errors - ABS failure, brake distribution failure and PSM failure. Car drove normally. Turned off and restarted the car, faults were cleared but came right back less than a mile later.
hooked up my Durametic and got two codes: 4440 steering angle sensor faulty & 4222 wheel speed monitoring. Checked left rear rotor after removing the tire - all connections looked tight. Didn’t check the right yet.
any thoughts? I had an intermittent PSM failure from time but these issues didn’t start to after the rear tires were replaced.
What size tires did you install and what size fronts are you running? If the fronts and rears have different rolling circumferences by more than about 3% the PSM system will do this and if on an AWD car, you can also destroy the transfer case.
Fronts are 225/40/18. In the rear went from 265/40/18 to a 275/40/18. Not that much of a change.
been reading some posts that PSM / ABS errors can be caused by a defective brake light switch. Mine seems functional as it works consistently. Plus it wasn’t flagged on the Durametic.
What the heck is a Brake Distribution Failure anyway?
That's your problem. With those front and rear sizes youve created almost a 6% rolling circumference differential which is too large for the PSM system to manage. Here's the comparison of the 2 tires you're now running. Ignore wheel width and offset as it's not important for this analysis. Your previous pairing at a 5.47% difference wasn't very good either but was evidently below the failure threshold of the PSM system.
So you've gone from a 4.6% circumference difference front-rear to 6%. Doesn't sound like much, but it's possible that could be over the threshold where the ABS/PSM starts throwing errors.
Interesting. I’ve run 295/30/18 in the rear with the same front 225/40/18 with only intermittent PSM errors - like once every few weeks. Now with the 275/40/18 rears it’s every Mile.
Interesting. I’ve run 295/30/18 in the rear with the same front 225/40/18 with only intermittent PSM errors - like once every few weeks. Now with the 275/40/18 rears it’s every Mile.
295/30 rears are less than 0.5% different than the fronts. Of all the sizes you've listed, that's the best choice so far! Do you understand how section width and aspect ratio on a tire work? The aspect ratio is a percentage of the section width so a 295 / 30 has a 295mm tread width and the sidewalk height is 30% of that. Using pi x diameter you can calculate the rolling circumference, or you can just punch the numbers into www.willtheyfit.com and it will do it for you.
Update. So I put my OEM wheels and tires back on. Drove for about 10 miles. Zero errors. Looks like the larger tires were the issue.
Thanks for the assistance!
Great to hear and good data points for us on percentages from the sizes you were running. Looks like around a 5.5% differential is what triggers the issue.
10-27-2022, 10:34 PM
PSM, ABS, Brake Distribution Failure
