I was driving my 2002 C4S today when another driver decided to cut in front of me and block the road to get her coffee in the drive through. Anyway, I held my horn for a good 30 seconds to annoy her enough to move, but afterward my onboard computer said the PSM and ABS have malfunctioned and to drive to the work shop. I shut down the car and restarted and everything was back to normal. I ran my scanner on the car and it showed a stored code of P4460 "pressure sensor" stored under ABS/PSM.

Does anyone know what this code is exactly or why it would have been thrown for holding my horn while stopped?

 

I am not familiar with this code... try clearing it and see if it comes back.

 

it is not unusual to get an ABS/PSM code from low voltage...the long horn application could have resulted in a low voltage or battery drain that tripped the code...get it cleared and see if it comes back..also, don't be surprised if you need a new battery soon

 

I got that code after car was in cold wet weather.Replaced battery.Not heard from since.

Terry

 

Thanks for everyone's insight. I cleared the code and it was fine for the rest of the day and the following day. With regards to the last post, that day the code came up it had rained the night before and it was morning when it went off after I held my horn. The rest of the day and the following was sunny and dry. However, it rained and was cool (15C) last night and the code came back first thing this morning and through the day. Each time I shut the car off the ABS/PSM would disappear UNTIL I re-applied the brakes at the next corner or stop light. It was fine after the day warmed up, but by this evening the code came back. It just rained again tonight and I suspect tomorrow morning will throw the code again, even though I just erased it right now.

My car is not garaged right now and I know my battery is weak because I had to slow charge it about a month ago. Perhaps I will install an Optima Red Top and hope this issue won't come back. I will try the battery idea first and let you guys know if it fixes it. Makes sense with what happened to tw02996c4s, my car has been outside in damp & cool weather with a weak battery.

 

I tried to get an Optima battery for mine but they were all to tall.I ended up with a larger battery and had to weld a nut on the bottom of the battery box and repaint.PITA.One more thing I noticed a couple of the coils,it looks like some of the isolation is peeling.I'm wondering if that could cause intermittent problems in wet weather.But I would think it should show up as an ignition malfunction

Terry

 

You're probably correct. If the coil was faulty and water seeped in it would come up as a misfire. I just replaced all coils and plugs a couple weeks ago, so I doubt this is my issue. I am going to throw in a new battery and see what happens. This site is great for these bits of information. Pfaff Porsche stealership would take me to the cleaners with diagnosing and probably never fix it anyway.

 

Well, I fitted a Red Top Optima battery today and it had plenty of clearance ... not sure why it didn't fit into your C4S "tw02996c4s".

Anyway, I instantly heard the car start cranking much stronger since the old Interstate battery I had was 700CCA and the new Optima I put in has 1000CCA. However, to no avail, the ABS/PSM lit up to tell me it had a malfunction once again.

Does anyone have a manual or something to tell me what code P4460 pressure sensor is exactly??? I tried Google, but have had no luck in finding any meaning for it. Could it have anything to do with my brake pads being low? I think there are wear sensors in the pads that will signal the instrument panel to tell me when they're low? The car doesn't vibrate or anything when applying the brakes, but I do think the pads are getting down there and needing replacement soon. I would estimate there is about 1/4" to 3/8" of pad left on the fronts and about 1/4" on the rear pads.

If anyone could help me out it would be appreciated, rather than going to the dealer

 

FIXED! For those interested in knowing what P4460 "pressure sensor" is, it's the brake light pedal switch under the dash panel. What happened was my show probably hit the switch when I quickly applied the brakes and loosened it. A local mechanic looked up the code for me free of charge and told me to check the plug. It looked connected, but had some wiggle room and I firmly pressed it back into place. Drove around and ABS/PSM never came back on now One sign I never checked was that my brake lights never worked while this malfunction occurred ... luckily nobody rear ended me.

If anything else occurs I will keep adding to this post.