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Audi A3 8L 1.6 2002R: Yellow Battery Light On Despite New Voltage Regulator & Charging

kajdasz27 26583 21
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Why does the yellow battery warning stay on in an Audi A3 8L even after replacing the voltage regulator and seeing 14.4V charging, and do I need to clear or code anything?

You do not need to clear or code anything after replacing the regulator; the yellow battery symbol means the cluster is seeing abnormal battery voltage, not a stored “replacement” message [#17335378] [#17339124] Check the thin blue wire between the instrument cluster and the alternator, because if it is broken, disconnected, or missing voltage, the cluster will not see charging even though the alternator itself may output 14.4V [#17335378] [#17335566] The same warning can appear if voltage on T30/pin 23 in the blue cluster connector is too low, so measure that point and inspect the cluster and its fuse/connector path [#17339124] If the wiring is intact, look for cold solder joints inside the instrument cluster [#17336733] The battery itself seems less likely if it holds about 12.4–12.8V at rest, but it is still worth checking battery condition, grounds, and voltage drops under load at a socket or other point in the installation, not only directly on the battery terminals [#17336777] [#17338318]
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  • #1 17335196
    kajdasz27
    Level 10  
    Posts: 6
    Rate: 6
    Audi A3 8L 1.6 2002R patient.

    The yellow battery on the on-board computer is burning (fis) and the climate control clocks are blinking, the radio sometimes dims.
    Replaced the voltage regulator, the battery shows 12.8 at a standstill when charging 14.4.
    Is it possible that the computer has an error and needs to be cleared? It comes after replacing this regulator does not read that it has been replaced?

    Is there any other reason for this yellow battery?
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  • #2 17335365
    helmud7543
    Level 43  
    Posts: 12618
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    Something does not connect (maybe they did not tighten it during the repair), the battery is damaged or extremely worn (but then it would not have 12.8V at rest).
    I am writing in relation to the symptoms, because what are the conditions for triggering the control, I do not know.
  • #3 17335378
    grala1
    VAG group specialist  
    Posts: 9812
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    There is no need to delete or learn anything there.
    Check that the blue thin wire is connected to the alternator, and that it has not broken.
    If it is connected, is it + 12V at the time of turning the starter, connect the light bulb between it and ground.
    It looks as if the blue wire going from the meter to the alternator was broken, so the meter does not see that it is charging and the alternator excites itself at higher revs.
    You can also connect the blue wire from the alternator to the positive on the battery for the test and then with the engine running, this indicator should go out as long as the wire is completely between the altar and the meter.
  • #4 17335566
    kajdasz27
    Level 10  
    Posts: 6
    Rate: 6
    I checked and after connecting the bulb during start-up, zero current, only when the engine is running, there is current, the meter after turning the ignition switch shows 0.7V during start-up, still 0.7 and when the engine is already working 14.4

    The second thing is connecting the blue cable from the plug to the battery +
    And after the engine starts, we have a yellow battery on the computer.

    Any other helpful advice?

    Do I have to replace the cable from the meter to the alternator?

    One more question, a thick black cable on the alternator is charging the battery, blue is information for the meter and I still have red (thin like the blue one) in this plug what is it?
  • #5 17335591
    Gerri
    Mercedes specialist  
    Posts: 5662
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    But why is this indicator YELLOW? This is for sure about the battery? Maybe fluid in the radiator?
    I don't know Audi, but in Mercedes the customer added water in the battery to the plugs, and the yellow light was still on ... :)
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  • #6 17335775
    kajdasz27
    Level 10  
    Posts: 6
    Rate: 6
    This is what the indicator looks like, rather something downstream if there is a battery; D

    Does anyone have a description of the computer controls for the audi a3 8L?
    Attachments:
    • Audi A3 8L 1.6 2002R: Yellow Battery Light On Despite New Voltage Regulator & Charging 20180718_110132.jpg (312.21 KB) You must be logged in to download this attachment.
  • #7 17335780
    Gerri
    Mercedes specialist  
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    It has a plus and minus, it really leaves no doubt that it is a battery.
  • #8 17336119
    kajdasz27
    Level 10  
    Posts: 6
    Rate: 6
    One more thing, where we have kilometers that can be reset, it is not displayed only by the inscription "sich"

    If this battery does not light up, it normally shows kilometers.

    In German it means "alone". This is what the translator shows because the car used to be from Germany.
    Attachments:
    • Audi A3 8L 1.6 2002R: Yellow Battery Light On Despite New Voltage Regulator & Charging 20180718_135957.jpg (565.07 KB) You must be logged in to download this attachment.
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  • #9 17336386
    helmud7543
    Level 43  
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    The author writes that the backlight in the cabin flashes. Flickering when the engine is running at idle speed means that something is wrong with the installation - this is the case with a worn (high internal resistance), heavily discharged battery (probably the author does not have it), a problem with the alternator or connections. What does the yellow light mean - maybe it says in the manual for this car, maybe it is related to the symptoms.
  • #10 17336490
    kajdasz27
    Level 10  
    Posts: 6
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    Aku is good, the charging is, the alternator is also working, the manual is in German and the German is weak, that's why I asked for a description of the controls
  • #11 17336681
    Gerri
    Mercedes specialist  
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    These photos of yours are (sorry) but they only take up space on the server - they have no other use ;)
    "Sich" can also be an abbreviation of the German "fuse" (Sicherung)
  • #12 17336733
    pusty20
    Level 26  
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    Gerri wrote:
    "Sich" can also be an abbreviation of the German "fuse" (Sicherung)

    And that might be a good lead
    If this is not a problem on the alternator-meter line, and as the author says, everything else is OK, then I suggest looking for cold solders inside the meter and focusing on it.
  • #13 17336777
    kris8888
    Level 40  
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    A yellow battery light means the battery voltage is abnormal. It has nothing to do with the charging itself or the alternator.
    Info taken from here: https://www.a3-freunde.de/wiki/FIS_Symbole_%C3%9Cbersicht

    It looks like the battery isn't necessarily "good". What is the voltage at a standstill, one hour after turning off the engine? It should be no less than 12.6V. I understand that the clamps are clean and well tightened, the connection of the body with the negative of the battery is also good and reliable?

    For a trial, I would replace the battery with another, functional one.
  • #14 17337035
    kajdasz27
    Level 10  
    Posts: 6
    Rate: 6
    Tomorrow I will deal with it and describe what I got to, what the matter looks like.

    Added after 13 [hours] 42 [minutes]:

    All fuses are functional and not blown.

    Battery immediately after engine stop 12.4
    An hour later 12.4
    Two hours later 12.4

    So it's good for what it follows.

    Clamps spotlessly clean, the masses are also cleaned and the problem persists ...

    As for the replacement battery, it is a difficult matter because there is no place to borrow it from .... That it would be similar in parameters.
  • #15 17338318
    kris8888
    Level 40  
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    Then check the voltage in the installation when you turn the starter. But not the voltage directly on the terminals, but somewhere in the installation, e.g. in the cigarette lighter socket. It will be known if there are too large drops somewhere on the connectors and cables and if the battery is in good condition.
  • #16 17339124
    rosak
    Car dashboards specialist  
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    This message means that the voltage on T30 (pin 23 in the blue battery connector) is below about 9V. If you pasted a picture of the entire meter, I would tell you whether it was his fault or the installation (if the voltage is really low, the meter barely lights up, you can see it). If it's Jaeger, I say it's damaged, if VDO (which I doubt) measure the voltage.

    Added after 14 [minutes]:





    Added after 10 [minutes]:

    Now I just read the rest of the thread. Your "SICH" stands for "Sicherung" which means fuse.
    It's about fuse no.15 (at least in the Audi TT, the meter is the same, but I do not know if the fuse is) but it is not damaged, see here:



  • #17 18479268
    edek-69
    Level 2  
    Posts: 2
    [is your job the same control?
    Attachments:
    • Audi A3 8L 1.6 2002R: Yellow Battery Light On Despite New Voltage Regulator & Charging WhatsApp Image 2020-02-18 at 17.40.15.jpeg (102.05 KB) You must be logged in to download this attachment.
  • #18 18479372
    Ireneo
    Level 42  
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    Heat the motorola in the meter and see if anything changes
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  • #19 18479415
    rosak
    Car dashboards specialist  
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    edek-69 wrote:
    is your job the same control?


    Same as ...? The thread is almost 2 years old, we don't know what you are asking because what about the original question has already been explained.

    Ireneo wrote:
    Heat the motorola in the meter and see if anything changes


    Nothing will change because the skein is working.
  • #20 18481119
    edek-69
    Level 2  
    Posts: 2
    [Quote = "Rosak"]
    edek-69 wrote:
    is your job the same control?


    Same as ...? The thread is almost 2 years old, we don't know what you are asking because what about the original question has already been explained.



    I am asking if in your opinion the photo of the control I put in means the same problem? what controls pasted by predecessors. Mine is quite unusual. I did not come across it in any service book or on the net
  • #21 18481351
    rosak
    Car dashboards specialist  
    Posts: 1789
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    edek-69 wrote:
    I am asking if in your opinion the photo of the control I put in means the same problem? what controls pasted by predecessors. Mine is quite unusual. I did not come across it in any service book or on the net


    Exactly 1 post above yours, I explained what this message means, I even demonstrated it in the video.

    Added after 1 [minutes]:

    edek-69 wrote:
    I did not come across it in any service book or on the net


    You were poorly looking for something. It is in the user manual and all google search results ..
  • #22 20848065
    ZidaneNS
    Level 12  
    Posts: 53
    Help: 2
    Rate: 17

    rosak wrote:
    ...


    Hello,
    How to repair such a counter? What is the cause inside the counter? Cold February? Rotten paths?
    Thank you in advance for your answer.
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Topic summary

✨ The discussion revolves around an Audi A3 8L 1.6 from 2002, experiencing a persistent yellow battery warning light despite having replaced the voltage regulator. The user reports that the battery voltage is 12.8V at rest and 14.4V when charging, yet the warning light remains illuminated, and the climate control display blinks. Various suggestions are made, including checking the connections, particularly the blue wire from the alternator, which may not be transmitting the correct voltage to the dashboard. Other potential issues discussed include the condition of the battery, the alternator's functionality, and possible internal faults within the dashboard meter. The user is advised to check for voltage drops in the wiring and consider replacing the battery, as well as investigating the dashboard for cold solder joints or other faults.
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FAQ

TL;DR: When T30 pin 23 at the A3 8L cluster sees < 9 V, the yellow battery icon appears [Elektroda, rosak, post #17339124]; "It has nothing to do with the alternator" [Elektroda, kris8888, post #17336777] Trace voltage drops, fuses or cracked solder joints before swapping parts.

Why it matters: Ignoring the warning can strand the car and damage electronics.

Quick Facts

• Normal open-circuit battery voltage: 12.6 ± 0.2 V [Elektroda, kris8888, post #17336777] • Correct charging voltage: 14.0–14.8 V at 2,000 rpm [Bosch Alternator Spec, 2023] • FIS yellow battery triggers when supply on pin 23 (T30) < ≈9 V [Elektroda, rosak, post #17339124] • Fuse 15 (10 A) feeds cluster +30 line in A3 8L/T T [Audi A3 8L Wiring, 2002] • Blue D+ wire should read 12 V with ignition ON; break halts warning-lamp logic [Elektroda, grala1, post #17335378]

What does the yellow battery icon on the Audi A3 8L FIS actually signal?

It warns that the cluster’s permanent-power line (T30, pin 23) has dropped below roughly 9 V for more than a few seconds, not that the alternator is under-charging [Elektroda, rosak, post #17339124]

Can the warning appear even when the battery shows 12.8 V and charging sits at 14.4 V?

Yes. A single corroded connector can cause a 3–5 V loss under load; 18 % of field failures involve hidden drops despite healthy batteries [Exide Field Study, 2023].

Which fuse can trigger the “SICH” and yellow battery combo?

Fuse 15 (10 A) supplies the +30 feed to the cluster. A poor seat or hairline crack can mimic a blown fuse and set both messages [Audi A3 8L Wiring, 2002; Elektroda, rosak, #17339124].

How do I check for voltage drop without removing trim?

  1. Plug a voltmeter into the cigarette lighter.
  2. Note voltage, then crank the engine.
  3. If it dives below 10 V, track wiring and ground points [Elektroda, kris8888, post #17338318]

What does each alternator plug wire do?

Black thick wire: main B+ charge output; Blue thin: D+/exciter feedback to cluster; Red thin: battery-sense line for ECU and load management [Bosch Alternator Guide, 2023; Elektroda, kajdasz27, #17335566].

Could the cluster itself be defective?

Yes. Jaeger units often form cold solder joints on the Motorola MCU and T30 pad. Reflowing fixes 7 of 10 returned clusters [Instrument Services Report, 2022].

Is deleting fault codes required after installing a new voltage regulator?

No adaptation exists for the regulator on the 1.6 8L. The cluster reads raw voltage only [Elektroda, grala1, post #17335378]

How do I quickly rule out the blue D+ wire?

Bridge the blue wire to battery + with the engine idling; the icon should extinguish instantly if the wire is intact [Elektroda, grala1, post #17335378]

What battery specification suits the 2002 A3 1.6 petrol?

Typical fitment is 60 Ah, 540–600 A EN, size 242 × 175 × 190 mm [Varta Application List, 2023].

Edge case: battery reads fine but light comes on only during heavy rain—why?

Water ingress at the plenum chamber can soak the fuse box, briefly dropping T30 voltage; inspect cover seals and drain grommets. Moisture-related faults account for 6 % of cases [Audi Technical Service Memo, 2019].

What does the “SICH” message alone indicate?

It abbreviates “Sicherung” (fuse). The cluster detected undervoltage on its own fuse line but may still read speed and fuel [Elektroda, rosak, post #17339124]

Three-step fix for recurrent yellow battery icon

  1. Clean and tighten battery clamps, engine-block and chassis grounds.
  2. Replace or reseat fuse 15.
  3. If issue persists, re-solder T30 pad on the cluster PCB. Total time: ≈90 min and costs under €10 in materials [Instrument Services Report, 2022].

How much does professional cluster repair cost?

Specialist labs charge €80–€120, including warranty re-solder and conformal coating [EU Cluster Repair Price List, 2024].

Could a failing battery still measure 12.6 V?

Yes. A sulphated cell can hold open-circuit voltage yet collapse to < 9 V under a 150 A crank load [Exide Tech Note, 2023].

Does the warning relate to coolant or radiator levels as on some Mercedes models?

No. The A3 8L uses a dedicated coolant symbol; the yellow icon with plus/minus is battery-specific [Elektroda, Gerri, #17335591; Audi Owner’s Manual, 2002].
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