D90971 Dubai · Mercedes A250 · Blue

1) SYMPTOM SUMMARY
Customer reports "turbo not working" on a Mercedes A250 (VIN WDDBF4EB2FJ325976, mileage not recorded). No prior repair history flagged, so this is not a comeback. Technician's diagnosis was not completed before the customer left the vehicle overnight — no codes, live data, or visual findings recorded yet. "Turbo not working" is a customer-perceived symptom (likely reduced power / hesitation / whistling noise / limp mode) and needs to be translated into a measurable fault before any turbo-related part is condemned.
ملخص: العميل يشتكي من "التيربو ما يشتغل" على مرسيدس A250، والفحص لم يكتمل بعد ولا توجد بيانات مسجلة.

2) LIKELY CAUSES (ranked cheapest-to-confirm first, not by probability)
1. Stored fault code(s) triggering limp/reduced-power mode (boost underboost/overboost, actuator position, sensor circuit) — most common reason customers say "no turbo power," and it's free to check with a scan.
2. Vacuum or charge-air leak (intercooler pipes, boost hoses, connectors) — very common on A250/M270 engines, causes soft/no boost, cheap to inspect visually.
3. Electronic wastegate/turbo actuator fault (stuck, miscalibrated, or communication fault) — common wear item, confirmed via active test not by guessing.
4. Boost/MAP or MAF sensor signal fault feeding wrong data to ECU — cheap to verify with live data before condemning turbo.
5. Diverter/bypass valve leaking or stuck — cheap to inspect once cover panels are off.
6. Turbocharger mechanical failure (worn bearings, damaged compressor/turbine wheel, oil starvation) — most expensive, must be proven last (boost scope test + visual inspection of wheel play/oil residue), never assumed first.
الأسباب المحتملة مرتبة من الأرخص للتأكيد: أكواد أعطال/وضع الطوارئ، تسريب هواء الشحن، عطل محرك التيربو (actuator)، عطل حساس الضغط، صمام bypass، وأخيراً عطل ميكانيكي بالتيربو نفسه.

3) TEST SEQUENCE
1. Connect Autel MaxiSys Ultra S2 → run Auto Scan / Topology to pull all module codes (not just engine). Expected: DTCs related to boost pressure, turbo actuator, or intake system.
   - If codes found related to boost/actuator/sensor → go to step 3 for that circuit.
   - If no codes → go to step 2.
2. Visual/physical inspection (free): check charge-air pipes, clamps, intercooler, vacuum lines, and turbo actuator linkage for cracks, disconnection, or looseness. Expected: intact, no leaks, actuator moves freely by hand (engine off).
   - If damage/leak found → repair/replace pipe or clamp, then re-test drive and re-scan.
   - If no visible fault → go to step 3.
3. Live Data PIDs (Autel): monitor Boost Pressure (actual vs. commanded), Turbo Actuator Position (actual vs. commanded), Intake/MAP sensor value, and Barometric pressure at idle and during a road/data-logged test drive. Compare actual vs. commanded boost — get exact spec/tolerance from TOPIx/ALLDATA for this VIN.
   - If actual boost tracks commanded correctly → turbo/actuator hardware likely OK, suspect sensor calibration or software — go to step 4.
   - If actual boost lags or never reaches commanded → go to step 5.
4. Autel Active Test: command the wastegate/turbo actuator through its range (if supported for this VIN) and watch live data response. Expected: actuator position changes smoothly and matches commanded value with no error stored afterward.
   - If actuator responds correctly → cause is elsewhere (fueling, exhaust restriction, sensor) — broaden diagnosis beyond turbo.
   - If actuator response is slow/erratic/absent → go to step 5.
5. Manual/mechanical actuator check: with engine off, apply the actuator's control signal or manual test per TOPIx procedure and check for free, full-range movement; check for oil residue at actuator diaphragm (sign of failure). Expected: full smooth travel, no binding, no oil contamination.
   - If actuator sticks/binds/leaks oil → actuator or turbo unit is the root cause — confirm with step 6 before ordering parts.
   - If actuator is free/dry → go to step 6.
6. Boost leak-down/pressure test and turbo shaft play check (requires removing intake ducting): pressurize the charge-air system to manufacturer spec (get exact test pressure from TOPIx/ALLDATA for this VIN) and check for leaks; check compressor/turbine wheel for excess axial/radial play by hand. Expected: holds pressure within spec, minimal wheel play.
   - If leak or excess play found → this is the proof needed to condemn the turbo. Order part.
   - If no leak/play found → re-evaluate fueling, exhaust back-pressure, or ECU software/coding fault using Autel scope/live data before ordering any part.

تسلسل الاختبارات: من الأرخص للأغلى — سكان أكواد، فحص بصري لتسريب الهواء، بيانات حية للضغط والـ actuator، اختبار فعلي (Active Test) للـ actuator، فحص يدوي للـ actuator، وأخيراً اختبار تسريب الضغط وفحص لعب عجلة التيربو قبل اعتماد استبدال القطعة.

4) DATA TO COLLECT
- Full DTC list (all modules) with freeze frame data, including any prior/pending codes.
- Boost pressure: actual vs. commanded, at idle and under load/road test.
- Turbo actuator position: actual vs. commanded.
- MAP/boost sensor raw value and voltage.
- Barometric pressure reading (for altitude/ambient correction reference).
- Photos of any visible leak point, damaged pipe/clamp, or oil residue at actuator.
- Result of active-test actuator sweep (pass/fail, response time).
- Boost leak-down test result and turbo wheel play (if step 6 performed).
- Customer's exact description of symptom (noise? power loss? warning light? intermittent or constant?) — confirm with customer when car returns.

البيانات المطلوب تسجيلها: كل الأكواد، ضغط الشحن الفعلي مقابل المطلوب، موضع الـ actuator، قراءة حساس الضغط، صور أي تسريب أو تآكل، ونتيجة اختبار التسريب ولعب عجلة التيربو.

5) SAFETY
- Engine bay work near turbo/exhaust involves hot components — allow engine to cool before hands-on inspection (steps 2, 5, 6).
- Boost pressure/leak-down testing (step 6) uses shop air under pressure on the intake system — follow TOPIx pressure limits to avoid damaging seals/sensors.
- Standard PPE (gloves, eye protection) when removing intake ducting.
السلامة: احذر من حرارة التيربو والعادم، اترك المحرك يبرد قبل الفحص اليدوي، والتزم بحد ضغط الهواء المحدد في TOPIx عند اختبار التسريب.

DRAFT — the technician must verify before any part is ordered. مسودة — القرار النهائي للفني.