P1502 fault code

[PPP]

My turn to contribute to this saga and irritating fault code. Background is the car was first registered April 2000, 90,000 miles and was running without fault before the problem arose. It's a 986 Boxster S.

The symptoms are as listed by other owners on lots of forums - erratic idle and not revving above 2000 rpm. The code can be cleared while the car is running or before starting and then it will run perfectly but on a restart the code is triggered again and the rough running resumes. There is only one fault code which is P1502 DVE spring test fail. I have taken the following steps which made no difference:

Replaced the throttle body with one from a perfectly running car.

Cleaned connections and checked for air leaks.

Rapid switching on and off of the ignition.

Left the car with the battery disconnected for 24 hours and tried the adaptation process.

Ensured the battery is fully charged and holding charge.

Changed the fuel relay to a known good one.

I don't think the adaptation process is working. When I switch on the ignition I can feel a single distinct click from the throttle body but I don't hear any humming or other noise, however long I leave the ignition on for without starting.

This makes me think the code is correct and the spring test is failed but since it's repeated with a working replacement throttle body it cannot be mechanical but is more likely to be signal based. I'm obviously reassured it cannot be a serious issue as the car runs perfectly with the code cleared.

I now want to swap the DME and find it's bolted in with two normal 10mm nuts and five unusual splined nuts. Can anyone tell me what tool I need for these splined nuts as there doesn't appear to be enough space around all of them to get a socket on?

[JFP in PA]

P1502 is the code for end stage fuel pump relay, short to plus.

Three possible causes:
1. Bad relay
2. Wiring to relay shorted to B+
3. ECM faulty

[PPP]

Originally Posted by JFP in PA

P1502 is the code for end stage fuel pump relay, short to plus.

Three possible causes:
1. Bad relay
2. Wiring to relay shorted to B+
3. ECM faulty

Thanks for the reply.

I note what you say about the code being related to the fuel pump relay but that's not what the code reader is saying - it's saying it's a DVE spring test fail, which to me seems to fit with the click I get from the throttle body when the ignition is switched on. I have read that I should hear the motor running in the form of a hum while the TB is recognised and the settings updated, Despite that, I have changed the relay for a known good one so it isn't that component.

When you say the ECM, is that your term for what I would call the DME or ECU?

Can you advise regarding the spline nuts?

[redpepperracing]

Originally Posted by PPP

Can you advise regarding the spline nuts?

I just looked at mine and it is all held on with M10 nuts, so not sure what is up with yours. They are likely male Torx, from the way you describe them, I got a Torx kit on Amazon that has all the ones I've ever needed for working on the Boxster.

A picture would help us with identifying them.

[JFP in PA]

Originally Posted by PPP

Thanks for the reply.

I note what you say about the code being related to the fuel pump relay but that's not what the code reader is saying - it's saying it's a DVE spring test fail, which to me seems to fit with the click I get from the throttle body when the ignition is switched on. I have read that I should hear the motor running in the form of a hum while the TB is recognised and the settings updated, Despite that, I have changed the relay for a known good one so it isn't that component.

When you say the ECM, is that your term for what I would call the DME or ECU?

Can you advise regarding the spline nuts?

That information came directly from Porsche's OBD II diagnostic manual for your car, so it is correct.

Not surprised a non-Porsche specific diagnostic tool would give you incorrect information; we see that almost daily when customers come in telling use their car has this or that problem, and when we rescan the car with the proper tool, get something completely different. Unfortunately, with diagnostic tools, you gets what you pays for......

ECM=DME

[PPP]

Originally Posted by redpepperracing

I just looked at mine and it is all held on with M10 nuts, so not sure what is up with yours. They are likely male Torx, from the way you describe them, I got a Torx kit on Amazon that has all the ones I've ever needed for working on the Boxster.

A picture would help us with identifying them.

Here you go:

[PPP]

Originally Posted by JFP in PA

That information came directly from Porsche's OBD II diagnostic manual for your car, so it is correct.

Not surprised a non-Porsche specific diagnostic tool would give you incorrect information; we see that almost daily when customers come in telling use their car has this or that problem, and when we rescan the car with the proper tool, get something completely different. Unfortunately, with diagnostic tools, you gets what you pays for......

ECM=DME

Yes I now see Porsche used that code for two different faults but the spring one my reader is reporting actually refers to the earlier cable throttle cars.

What would you recommend by way of a scanner or will I be into spending too much money for an amateur? I am using the icarsoft Porsche version.

[JFP in PA]

I have never been a fan of the iCarsoft units, the constantly over promise and under deliver on capabilities, which they continue to say will be available in a future update that never seems to materialize.

Obviously, the best would be a legitimate PIWIS system, which is lease only and opens at $20K for the first year. And don't even think about spending your $ on PIWIS clones, many of them are incomplete, cannot be updated, and some can actually damage the car's electronics. So, unless you are willing to spend mega $, I would go with the Durametric software. Not as capable as the PIWIS system, but much better than a lot of companies selling "made for Porsche" standalone units that are mostly global OBD II junk with a couple of Porsche specific capabilities thrown in for a higher price than a global OBD II unit.

[PPP]

I'm trying to work my way through this while waiting for an auto electrician to identify a possible short. Any advice wecomed.

As I have said, I don't think adaptation is working. When the ignition is switched on I can hear and feel a rapid double click from the throttle body.

What I noticed is that if I clear the code I can hear and feel a single click from the same area so I took the TB off and observed when you turn on the ignition the TB flap does a rapid double click and stops slightly open. When I clear the code the flap closes.

The fuel pump relay has been replaced with a good unit as has the TB and I cannot see any frayed wires anywhere.

In the meantime, can anyone tell me what else is on that fuel pump relay circuit?

I can't see any point in swapping the ECU because I gather it contains the immobiliser key and I don't want additional hassles with that.

I've been trying to think of anything that happened prior to this problem and all I remember is 1) running low on fuel once but not running out and 2) the union for the washers broke spraying fluid down the side of the battery box. There are two unconnected connectors there - one yellow and one black. Anyone know what they are for?

There has been no water ingress inside the car.

[redpepperracing]

Originally Posted by PPP

Here you go:

Those are obviously some kind of security nut, weird. Mine are just regular M10's:

[Nick2508]

Not sure if you have fixed the problem, but it seems to be specific to Boxster's (both 2.7 and 3.2) made in 2000.

I would again try turning the ignition on and off fairly quickly a gazillion times until you hear a solid clunk from the throttle body (and stop cycling the ignition switch, but leave it on), pause, then continue turning to start the engine.

If that fails, change the ignition switch.

To do that you need small hands and to be good at yoga....you'll understand when you try.

[warner_markk]

Thanks Nick2508! Haven't fixed it yet, but the "gazillion times" ignition dance sounds...fun? At least it's good to know it might be a 2000-specific issue. And yeah, the yoga pretzel pose for the switch replacement sounds familiar...maybe I'll just bribe a friend with smaller hands. I've been thinking about using some AI productivity tools to help me with my car's maintenance and repair. Sunshine Coast car detail shop

[Nick2508]

Hi Mark,

Hell yes, I'd pay good money to watch someone else do it for me!

I've just bought another switch (Meyle, 100 905 000, MEX0267) which is an OEM part for the Porsche 4A0-905-849/B.

It appears to be good quality and well manufactured.

I paid less than $20 including shipping (£15.01) and I can see that Stoddard do them in the US.

I originally replaced it in 2012 and I'm replacing it again 12 years later (it's starting to get less 'clicky' and feels worn out).

Not looking forward to the yoga pretzel moves though....😂

[LoneWolfGal]

Originally Posted by JFP in PA

I have never been a fan of the iCarsoft units, the constantly over promise and under deliver on capabilities, which they continue to say will be available in a future update that never seems to materialize.

Obviously, the best would be a legitimate PIWIS system, which is lease only and opens at $20K for the first year. And don't even think about spending your $ on PIWIS clones, many of them are incomplete, cannot be updated, and some can actually damage the car's electronics. So, unless you are willing to spend mega $, I would go with the Durametric software. Not as capable as the PIWIS system, but much better than a lot of companies selling "made for Porsche" standalone units that are mostly global OBD II junk with a couple of Porsche specific capabilities thrown in for a higher price than a global OBD II unit.

Man, I wish I'd seen this before I bought an iCarsoft. To add insult to injury, I found an identical unit in the box containing vinyl seat covers (which the previous owner had gotten to cover the original drivers seat, seeing as how its leather was in sad, sad condition). The other iCarSoft "Porsche-specific diagnostic unit" was under the vinyl covers. It was too late to return the first one, of course. So now I'm stuck with two of them. Maybe I'll take them to a meet and see if I can sell them, along with the vinyl seat covers. In the meantime, I'm psyching myself up to spring for a Durametric. Live and learn.