OBDII reader vs. Porsche System Tester?

My 996 has tripped the CEL a couple of times in the last couple of weeks. I went to an independent shop today to get the codes read. They inform me that the Porsche System Tester should be used because it gives more information with regard to a Porsche than a regular OBDII reader. They claim OBDII reader just gives generic codes while the PST2 gives more specific and detailed information in what caused the codes. Of course there is a substantial increase in cost to use the PST2 (only one guy uses it) vs. an OBDII reader. Is true or am I being upsold something that is really no benefit? Unfortunately I went to the Stealership to find out there take on this but there was no one there to confirm or deny this information (Porsche guy was on vacation). Any experiences?

The independent shop is giving you the straight scoope. The PST2 provides much more info and is capable of performing many more functions than a regular ODBII reader. It should. I think the run about $5K. Jim

PST2 gives word decriptions as well as code. I would get a free ODBII read at at auto parts place like Checkers and if the problem is not simple or persists get an ODBII readout. What have you changed lately, something like a K&N airfilter can foul a mass flow sensor leading to the CEL. PST2 is also the only way to reset some things like the air bag warning light, be sure to remove and reinsert the ignition key after the reset for things to be changed.

This unit reads codes and gives a terse description with a look-up CD you use on your PC. You can then list it here to get the full poop. --Dale

my OBD-II gives me codes and discriptions. I believe the pst can also reprogram things like auto door locks and your security system. I use the auto enginuity software on my pda. I t also reads engine specs and has a dynomometer program. Check it out www.autoenginuity.com they also have a program for you laptop.

An OBD2 reader will only interrogate and report faults related to emissions (generic) control related functions. Everything else inside the car (seats, windshield wipers, doors, HVAC, etc.) that has power running through it and certain parts (sensors) on the engine require a PST2 or PiWiS tester. If an OBD2 reader was an encyclopedia Volume A, the PST2 would be volumes A-Z. Hardware-wise there is almost no difference, the PST2 pulls codes off a different wire coming from the OBD2 bus but uses the same protocols. However, the protocols aren't documented so you have to pay extra $$$.

I understand the PST2 is a tool with much more capabilities as far what it can do with the car. I guess I wasn't clear with my question.... Assume the CEL is caused by an "emissions" problem (i.e. what is coming out of the tail pipe), does the PST2 give more information with regard to the cause of the problem or does it merely read and give the code in both number and word discription? For example ....Given that an OBDII code is thrown for somesome thing like "misfire cylinder 2". Does the PST2 give more information on what could have caused the misfire or what actually happened with the misfir occured or does it just indicate a misfire on cylinder 2 like the OBDII reader would? Or say the code is "02 Sensor." Does the PST2 give any additional information with regard to the sensor and why the code was tripped or does it just give the code?

Brain, Maybe a better way to describe the difference is that ODBII is a standard used my most car makers to read and diagnose what going on in the car. You may recall that early in the use of automotive computers the lack of a standard was a major problem for small shops that could not afford all the diagnostic equipment. Porsche follows the ODBII standard but extends it. The ODBII provides the basic codes but falls well short of providing all the information the PST2 does. When we were transplanting a 3.6L X51 into my 99 race car we had cam timing problems. The ODBII reader would tell us we were getting a cam sensor fault but nothing more. My mechanic borrowed a PST2 from the dealer and was able to download the "extended" data we needed to solve the problem. That's why I said to listen to your mechanic and have a PST2 scan done. It can't cost that much. Jim

Jim, Thank you. That is exactly the information I needed. PST2 here I come.

pst2 here i come?.... 5k!! I don't think so. if you got that kind of money to burn, let the dealer use their pst2 and you can buy an aero kit or wheels and suspension upgrade!!!

He didn't say he was buying one. Just having his codes read.

As Jim said...I'm not buying the PST2...I am just going to pay the shop to use the PST2 vs. a OBDII reader.

You may not even need to pay the shop just to let you know the problem. Here in South Florida they just run the test and give you an estimate for repair.