7 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHParasitic draw after using OBD2 port
Leading reported evidence
Disconnect battery
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 · Original poster
I've disconnected the battery to force a "reboot" and have done a repair cycle on the battery using a CTEK, but it still persists.
Leading evidence: 'Disconnect battery' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check any specific symptoms' (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.
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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.
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Suggestion · Original poster
I've disconnected the battery to force a "reboot" and have done a repair cycle on the battery using a CTEK, but it still persists.
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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Suggestion · Original poster
I wondered if perhaps the engine controller could be damaged by a bad reader cable/socket and never stop trying to communicate with the port in the car (even after a battery out reset).
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 · Original poster
Nothing else drawing power and a draw test confirms unless it is spiking randomly.
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Suggestion · Original poster
I wondered if perhaps the engine controller could be damaged by a bad reader cable/socket and never stop trying to communicate with the port in the car (even after a battery out reset).
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.
7 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: 20261026T142254Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hello folks,
I recently plugged in a code reader to my 996 C4S cab. After removing, I locked the car as normal. The next morning, the car would not start as the battery had discharged so had to use as battery booster. It's now a daily occurrence meaning something is draining the battery overnight. I've disconnected the battery to force a "reboot" and have done a repair cycle on the battery using a CTEK, but it still persists. I even swapped out the battery into another car to rule out an issue with the battery for a few days.
It could be a coincidence, so I'm about to start the process of trying to figure it out with a multimeter and pulling fuses, but wanted to ask if anyone had any experience with this (draw or battery issues after using diagnostic port) in the meantime in case it comes back to the ECU fuse being the culprit.
Thank you!
<<<<< over 50 years in the business in Dealerships and never came across a parasitic drain caused by using the OBD port...
FYI the total parasitic drain should be less than 30ma
OBD? Never on any of my Porsches or other cars.
I would first of all, have the battery tested. Then look at anything that has been modified (e.g. radio) or accessory that has been added to the car that needs or is incorrectly using constant power.
You plugged in a code reader. Why? Was the check engine light on? What type/brand of code reader? Agree with having the battery tested, or just replace it with new.
Electrical engineer here. Like everyone else has said here, the OBD reader is not related to your battery issue. It doesn't matter what car or the reader.
That's what I figured. I wondered if perhaps the engine controller could be damaged by a bad reader cable/socket and never stop trying to communicate with the port in the car (even after a battery out reset).
Draw is currently around 45mA, about an hour after locking the car.
Battery seems fine based on all tests so far. Nothing else drawing power and a draw test confirms unless it is spiking randomly. No changes to this car in a long time. CD multichanger makes a lot more noise than I would like on start up, but seems to settle.
Yes, to read codes. Curiosity, not to check any specific symptoms. Durametric. Changing the battery is arguably the cheapest and easiest next step, and beneficial for other reasons so that's my next move.
Roger.
No
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