5 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH99 Tiptronic Issue Shifting into 5th
Leading reported evidence
Replace /flushed
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that performed work without a confirmed outcome
1
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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
I believe it is save to assume that the ATF filter/fluid have never been changed/flushed.
Leading evidence: 'Replace /flushed' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check tires and pressure' (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.
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
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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
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Suggestion
It usually happens when someone replaces only one front tire.
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.
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Suggestion · Original poster
The independent shop essentially suggested that I need to replace the transmission.
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.
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Suggestion
Already tried to reset the adaptation values of the TCU?
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.
5 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: 20261027T175704Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Over the past few weeks, my 99 Tiptronic C2 coupe has stopped automatically shifting from 4th to 5th gear.
When I put the transmission into "manual" mode, the car will shift from 4th to 5th and back down with no issue.
The car has ~80,000 miles on it. A quick search of the forum revealed a few people asking about a similar issue years ago, but no real solutions or answers.
Anyone have a similar problem? Any suggestions?
Thanks!
Silk,
Thank you for the quick response:
I have managed to track down an incomplete maintenance history for the car. I believe it is save to assume that the ATF filter/fluid have never been changed/flushed. I've driven the car for two years and the issue just started recently.
I took the car to an independent Porsche focused shop in the greater Boston, MA area that seems to have all of the Porsche computer/diagnostic equipment (they were able to program a keyless entry fob and new key). I do not believe that they tried anything related to the adaptation values of the TCU. Is this something that can be reset without specialized equipment?
The independent shop essentially suggested that I need to replace the transmission.
Besides the Porsche specific tools also Durametric or a more advanced OBD reader has this functionality.
The Tip computer is a complex unit it uses input variables from all over the car. Thinking you can upshift manually makes that you have to look somewhere else then a mechanical issue. More something electrical or a module that throws a slightly off value which influences the TCU in automatic mode not to upshift.
Do you have any fault codes?
I found a thread on pelican parts where someone described a similar problem not shifting 4to5 in Auto, the brake light switch was the culprit.
http://forums.pelicanparts.com/porsc...lem-996-a.html
I know a bad brake light switch can cause a lot of strange problems. Maybe this is also one of them.
Check your tires and pressure. Maybe a faulty speed sensor of one of the wheels, ...
If you have no fault codes,
Make sure you tires are matching on the front. If there is a differance in size or even wear (one new and one near worn out) it will not shift into 5th gear.
The tiptronic is designed to not shift when in a turn as to not upset the suspension while turning., if there is a difference in diameter of the tires the trans thinks its in a turn all the time.
This simple fix has cause a many a technician to scratch his head. It usually happens when someone replaces only one front tire.
This is a source reference. Confirm exact model applicability in the original material.
