13 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH996.1 C2 Tiptronic _ Harsh 5th to 3rd downshift
Reported or suspected cause
transmission really starting off in first
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
I was told on my first experience to it starting off on 2nd in auto or manual mode was due to the transmission really starting off in first then shifting to 2nd.
Leading evidence: 'transmission really starting off in first' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'transmission really starting off in first' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check /' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Replace front wheel speed sensors and sent the abs module
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Because of erratic speed data on the scan tool and a previous 5527 code, I replaced both front wheel speed sensors and sent the ABS module to Module Masters for a rebuild.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause
I would do as others have suggested..check the trans mount/ change the fluids make sure they are topped off ...the if problem is still there replace the valve body ..
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Check/change transmission mount, common for the tips to do similar things as you describe when mount rubber has deteriorated.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
I would do as others have suggested..check the trans mount/ change the fluids make sure they are topped off ...the if problem is still there replace the valve body ..
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
I would do as others have suggested..check the trans mount/ change the fluids make sure they are topped off ...the if problem is still there replace the valve body ..
Replace front wheel speed sensors and sent the abs module
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Because of erratic speed data on the scan tool and a previous 5527 code, I replaced both front wheel speed sensors and sent the ABS module to Module Masters for a rebuild.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
I would do as others have suggested..check the trans mount/ change the fluids make sure they are topped off ...the if problem is still there replace the valve body ..
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
transmission really starting off in first
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
I was told on my first experience to it starting off on 2nd in auto or manual mode was due to the transmission really starting off in first then shifting to 2nd.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause
I would do as others have suggested..check the trans mount/ change the fluids make sure they are topped off ...the if problem is still there replace the valve body ..
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
13 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T144035Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi Everyone!
I am new to the Forum and loving it!
I am the proud owner of a year 2000 (Production 03/2000) Porsche 996 C2 Tiptronic with factory aerokit.
I love the car. However, I have recently noticed the following issue:
when cruising at approx 100km/h in 5th gear, and firmly pushing down the accelerator (also engaging kickdown) to - for example - overtake, the car shifts to 3rd gear and makes quite noticeable "bump" sound plus I can feel a clear puch coming from the gearbox. Like if the 3rd gear engagement is quite harsh.
The strange thing is that after making a couple of downshifts like this, the issue goes away almost completely until the next drive.
Other than this the tiptronic behaves perfectly.
Does anyone have any idea on what can be the cause of the above issue?
Thanks a lot in advance!
I would go for a change of fluids. Always the first step before going further with repairs on a gearbox. Do both the ATF and the diff oil, both easily done from under the car.
Check/change transmission mount, common for the tips to do similar things as you describe when mount rubber has deteriorated. Mine did similar when any hard shifting was attempted... Rubber in mount was destroyed.
jmo
I only trust my records, not the seller's that may probably give me an invoice from some other of his cars. Were both oils changed? Diff oil and ATF? I would also clear all adaptations in the gearbox (best way to do it is just remove the negative from the battery for 5min). FWIW, I once had a problem with a Touareg gearbox; all it needed was a software upgrade and it was fixed. I dont know about your gearbox, but later Mercedes ones were very stable and long lasting.
Nice hint! Thanks.
However, did yours get better after a couple of downshifts during the same drive?
Mine definetly does. First 5>3 downshift is harsh; then after 3 or 4 times it almost goes completely away.
Thanks!
Yes...
As rubber deterioration progressed it got more consistent. All dependent on how the mount 'settled' after hard shifts, as the tranny is constantly moving in the mount and different parts of the mount were worse than others.
It sounds to me like you have a sticking/worn pressure regulator in the valve body......Common problem on the ZF 5HP 19
I would do as others have suggested..check the trans mount/ change the fluids make sure they are topped off ...the if problem is still there replace the valve body ..
The ZF 5HP 19 is a very durable gear box, but does have it issues ....
hey, did you get to the bottom of this? Mine is exactly the same as described. Completely fine other than kickdown from 5th to 3rd feels like my gearbox is going to fall out!
Porschetech3, Rennlist members,
Title:
2001 996.1 Tiptronic: Code 93, Electrical Limp Mode at 85�C & ABS Comm Dropout — Valve Body or Swapping Trans?
Hey everyone, looking for some technical insight on an ongoing Tiptronic issue with a 2001 C2 I recently picked up. I can start a new thread if you think it's best.
The Backstory & Current Faults:
I bought the car with known shifting issues. Initially, I had codes 5527, P0722, P0733, P0734, and P0735. I’ve successfully resolved all of those, leaving me with just two remaining fault codes:
TCU Code 93:
CAN bus communication with the ABS control module interrupted.
CEL P1656:
(Transmission coolant valve/change-over valve circuit).
Current Symptoms:
Shifts "normally" at times, but occasionally slips on the 3-4 upshift.
Rushes through all gears way too quickly, regardless of speed or RPM.
Manual mode shifts fine
until
the transmission fluid hits ~85�C. At that exact point, Code 93 triggers, the trans goes into limp mode, and severe slipping occurs in automatic mode.
What’s Been Done So Far:
Because of erratic speed data on the scan tool and a previous 5527 code, I replaced both front wheel speed sensors and sent the ABS module to Module Masters for a rebuild. Tyler at MM has been great helping me troubleshoot.
During a test drive monitoring live data, all four speed sensors read flawlessly under 25 km/h. As soon as I crossed 50–55 km/h, the scan tool dropped connection entirely and flashed code 11070 (generic comm loss). At that exact moment, the ABS/PSM dash lights turned off.
Tyler bench-tested my unit against two other Bosch 5.7 modules and confirmed this drop-out behavior at 50 km/h is actually normal factory behavior—the ABS module intentionally kicks the scan tool out of diagnostic mode at that speed, and the dash lights turn off to signify it left diagnostic mode.
The Dilemma:
Since the ABS module's speed sensor communication behavior seems to be working as Bosch intended, I'm back to square one on why the TCU loses CAN communication and goes into limp mode specifically at 85�C.
I already bought a replacement transmission from a 46k-mile donor car. Given the symptoms (slipping when hot, P1656, and Code 93), should my next step be trying a rebuilt valve body with fresh solenoids, or should I just swap the entire transmission and call it a day?John
I have a lagging feeling on any push to jump to a higher gear that shows up under moderate acceleration.
I was told on my first experience to it starting off on 2nd in auto or manual mode was due to the transmission really starting off in first then shifting to 2nd.
Upshifts at speed also exhibit this behavior. I think torque converter isn't in directly connected to the gear and has to spin up and engage first.
NOTE: This is a SWAG based on something I read somewhere else⁰, but since I can't provide info to reference it, so take this with a substantial grain of salt.
,Low speed shift behavior is the default behavior. Dropping into fifth gear at 35 mph and 1200 rpm with an engine that doesn't to generate the hp or torque until until 3k is reached seems irresponsible.
Switching to manual and 4th gear at least the revs are in 2.1 or 2.3k range.
Using auto mode under most conditions return the best gas mileage, but apparently it is based on running in the lower rpm ranges. It's not the best way to operate it, but Porsche and Mercedes deemed it was acceptable for default behavior. So manual mode is preferred and running over 3k won't cause carbon buildup lugging it the way the auto operates and the car is perky enough to be a Porsche and not a slug
This is a source reference. Confirm exact model applicability in the original material.
