P0266: Cylinder 2 bidrag / balanseringsfel (Gränsvärde för jämn gång uppnått)
Felkod (DTC) P0266 indikerar att motorstyrenheten (ECM/PCM) har nått sitt maximala adaptiva bränslekompensationsgränsvärde för cylinder 2 i ett misslyckat försök att balansera motorns rotationshastighet och cylinderns effektutveckling. I moderna common rail-dieselsystem kör ECM kontinuerligt en funktion för jämn gång (Smooth Running Control) eller cylinderbalansering vid tomgång och jämn dellast. Genom att mäta variationer på mikrosekundnivå i vevaxelns acceleration mellan tändpulserna via vevaxelgivaren (CKP), trimmar ECM bränslemängden (mg/slag eller mm³/slag) dynamiskt per cylinder. Om cylinder 2 konsekvent levererar lägre vridmoment än snittet för övriga cylindrar - till följd av igensatta spridarmunstycken, internt läckage och för högt returflöde från reglerventilen, bristfällig kompression eller luftbrist - ökar ECM bränslemängden till cylinder 2. När detta korrigeringsvärde överskrider det övre kalibreringsgränsvärdet (vanligen +4.5 till +6.0 mg/slag) under en längre tid sätts P0266.
🚗 Körsäkerhet, typiska reparationskostnader & kontroll
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🚦 Körsäkerhet och mekanisk risk
Omedelbar mekanisk bedömning och behov av bärgareCylinder 2 bidrags-/balansfel - Effektutveckling under fabriksvärde
Vevaxelns acceleration för cylinder 2 halkar efter övriga cylindrar. ECU har nått gränsen för jämn gång-adaption i försöket att kompensera för otillräcklig bränsletillförsel.
MEKANISKA RISKER FÖR MOTORN VID FORTSATT KÖRNING:Obalanserade vridmomentspulser genererar vibrationer i kupén och accelererar slitaget på dubbelmassesvänghjulets dämpare. - 02
💰 Typisk verkstadsbudget
Förväntade kostnadsnivåer för reservdelar och arbeteLitet underhåll / Filter400 kr - 1 150 kr: Rengöring av bränslesystem och byte av bränslefilterRengöring av givare, bränslefilterbyte, säkringskontroll eller kontaktstiftsrengöring.
Byte av ventil / Sensor1 900 kr - 5 000 kr: Byte av spridare cylinder 2 med Bosch/Denso-originaldelByte av enskild komponent (tryckreglerventil, doseringsventil eller renoverad spridare).
Större översyn / Pump och spridare9 000 kr - 23 000 kr: Mekanisk kompressionsmätning eller reparation av topplockÖversyn av högtryckspump, ny OEM-spridaruppsättning eller byte av DPF-enhet.
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🧰 Snabb visuell kontroll utan verktyg
5-minuters garagekoll innan du ringer verkstaden11. Läs av livedata via OBD för cylinderbalansvärden (grupp 13 / 14 på VAG, Smooth Running på BMW).22. Utför returflödesmätning (leak-off): onormalt högt returflöde på cylinder 2 bekräftar hydrauliskt tryckfall i spridaren.33. Kontrollera om det finns bränslefukt eller sotläckage runt fästbulten och spridarsätet på cylinder 2. - 04
🛡️ Skydd mot feldiagnoser på verkstad
Konkreta frågor till mekanikern för att undvika onödiga komponentbyten""Bekräfta avvikelsen på cylinder 2 med ett returflödestest med mätglas innan spridaren demonteras.""
""Kontrollera relativ kompression över alla cylindrar för att säkerställa att felet är bränslerelaterat och inte beror på en bränd avgasventil.""
""Koda in den nya spridarens kalibreringskod i ECU och nollställ adaptionsvärdena för jämn gång.""
Teknisk anmärkning: Ställ dessa tekniska frågor till mekanikern innan du godkänner dyra offerter:
30-sekunders verkstadstriage
- Noticeable engine shudder, rough idling, and persistent vibration transmitting into cabin seats and steering wheel
- Slight hesitation upon tip-in acceleration and uneven engine acoustics under steady-state cruising
- Check Engine Light (MIL) illuminated with diagnostic trouble code P0266 stored in ECM memory
- Internal wear or carbon buildup on Cylinder 2 common rail fuel injector nozzle needle and spray holes
- Excessive injector backleak (leak-off) from Cylinder 2 control valve reducing delivered fuel volume into the chamber
- Mechanical compression deficiency in Cylinder 2 (worn piston rings, leaking intake/exhaust valve, or blown head gasket)
Connect scan tool live telemetry: compare Target Fuel Rail Pressure vs Actual Rail Pressure and log metering valve command PWM duty cycle during idle and road load.
Expensive Diagnostic Pitfall & Technical Reality
P0266 means Cylinder 2 has catastrophic mechanical piston or valve failure requiring engine block replacement ($3,500 - $6,000).
P0266 is an electronic Smooth Running Control limit code. The ECM measures crankshaft rotational acceleration after Cylinder 2 fires; if the required fuel trim compensation exceeds calibrated threshold limits (typically >±4.5 mg/stroke), P0266 is logged. In over 80% of verified cases, mechanical engine compression is completely sound. The root cause is an unprogrammed or incorrectly typed IMA/IQA injector calibration code, a partially clogged injector nozzle spray hole, or excessive internal control valve backleak dropping injection pressure.
Unnecessary engine replacement ($4,000+) vs verifying and reprogramming the 7-to-20-character IMA injector code into the ECM ($0 - $50) or rebuilding the injector ($120), saving thousands.
Mest påverkade motorer och insprutningssystem
Denna felkod påverkar främst följande diesel common rail-plattformar. Kontrollera din motorfamilj nedan för kända felmönster och artikelnummer:
BMW 2.0d / 3.0d (N47 / N57 / M57TU2)
Bosch CRI2.5 / CRI3.0 Common RailKänt fabriksfel: Injector balance drift beyond +/- 4.0 mg/stroke, glow plug control unit (BERU) power lead failure, DPF backpressure accumulation.
13537805428, 0445116024, 12217801201Renault / Opel 1.9 dCi (F9Q)
Bosch EDC15 / EDC16 Common Rail SystemKänt fabriksfel: Injector harness connector diesel seepage, glow plug tip carbon seizure, EGR valve soot accumulation.
7700107165, 0445110021, 8200542997Volkswagen / Audi 2.0 TDI (EA189 / CFFB / CFGB)
Bosch EDC17 Common Rail SystemKänt fabriksfel: Piezo stack degradation, injector harness terminal fretting, DPF differential pressure sensor silicone tube split.
03L130277, 0445110369, 076906051AFord / PSA 1.6 TDCi / HDi (DV6ATED4 / DLD-416)
Bosch CRI2-16 Common Rail SystemKänt fabriksfel: Injector copper washer blow-by (black death), injector cylinder circuit fretting corrosion, DPF pressure pipes heat cracking.
0445110239, 1980J7, 1618LPCylinder Balance & Injector Deviation Guide
Common rail diesel cylinder balance & smooth running diagnostic guide. Balance rates, mg/stroke deviation, P0263 misfire, compression vs injector test.
Styrkrets & Ställdonslogik
1. Dynamic In-Demand Fuel Metering
The Smooth Running Control (SRC) system acts as an electronic flywheel balancer. In a 4-cylinder four-stroke diesel engine, each cylinder fires every 180° of crankshaft rotation. Due to manufacturing tolerances, injector wear, and mechanical friction variations, each cylinder inherently generates slightly different torque impulses. The ECM's 32-bit microcontroller records the time required for the 60-2 target wheel teeth to pass the CKP sensor during each cylinder's expansion stroke. It calculates an instantaneous speed value (RPM_cyl). The ECM then calculates the deviation of Cylinder 2 from the engine mean speed (RPM_mean) and adjusts Cylinder 2 fuel delivery.
2. Closed-Loop PID Deviation Monitoring
Under nominal engine operating conditions at operating temperature (>80°C coolant), Cylinder 2 smooth running compensation operates within -1.0 to +1.0 mg/stroke. A positive trim value (+mg/stroke) indicates a weak cylinder where the ECM is adding extra fuel to push rotational speed up. A negative trim value (-mg/stroke) indicates an overly aggressive cylinder where the ECM reduces fuel. If the ECM's internal PID controller reaches +4.5 to +6.0 mg/stroke (or -4.5 to -6.0 mg/stroke) and the speed deviation persists for over 1,000 engine cycles, P0266 is logged. Unlike P0302 (which triggers on sudden misfires), P0266 captures progressive hydraulic wear or mechanical power degradation.
3. Diagnostic Trap: Normally Open (NO) vs Normally Closed (NC) Valves
Positive vs Negative Balance Diagnostic Rule: A positive balance reading (> +3.5 mg/stroke) on Cylinder 2 points to under-delivery: injector nozzle orifice carbon restriction, internal control valve high backleak (dumping pressure to return), or low mechanical cylinder compression. A negative balance reading (< -3.5 mg/stroke) indicates over-delivery: a leaking nozzle needle seat, nozzle dribble, or an incorrect/corrupted IMA/QR calibration code telling the ECM the injector is smaller than it actually is.
Elektriska & Hydrauliska referensvärden
Steg-för-steg Felsökningsprotokoll
Scan Tool Smooth Running & Trim Value Analysis
Connect a diagnostic scan tool and access Engine Live Data -> Smooth Running Control (SRC) / Cylinder Balance. With the engine fully warmed (coolant > 80°C) and idling in neutral with all electrical accessories off, record the compensation values for all cylinders. Normal cylinders operate within -1.0 to +1.0 mg/stroke. If Cylinder 2 is pegged above +4.5 mg/stroke, it is severely weak. If pegged below -4.5 mg/stroke, it is severely over-delivering.
Verify Cylinder 2 IMA / QR Calibration Code in ECM
Navigate to ECM Special Functions -> Read Injector Configuration / IMA Codes. Read the 16-to-30 character alphanumeric calibration string stored for Cylinder 2 and physically compare it with the code laser-etched on the head of the Cylinder 2 injector. If an injector was replaced without reprogramming this code, the ECM uses incorrect voltage and pulse width duration offsets, directly triggering P0266.
4-Channel Dynamic Injector Backleak (Leak-Off) Test
Attach graduated measurement tubes to the fuel return nipples of all four injectors. Clamp the return hose going to the fuel tank. Start the engine and allow it to idle for exactly 2 minutes. Measure fuel quantity collected. An injector with excessive backleak (> 25-35 mL/min or double the return of adjacent injectors) suffers from an eroded ball/valve seat, losing hydraulic pressure and causing P0266.
Oscilloscope Cranking Relative Compression Test
Hook an oscilloscope current clamp (600A) around the starter positive cable. Disable the high-pressure fuel rail pump or disconnect injector connectors to prevent engine starting. Crank the engine for 10 seconds. Observe the rhythmic starter current draw peaks. If the peak for Cylinder 2 is more than 10% lower than the other three cylinders, the root cause is mechanical (valves, rings, cylinder bore) rather than an injector failure.
Physical Injector Cross-Swap Diagnostic Test
Remove Cylinder 2 injector and swap it with Cylinder 1. Always fit brand-new copper sealing washers and new stretch clamp bolts. Enter the diagnostic scanner and reprogram the IMA/QR codes to reflect the new positions of Cylinders 2 and 1. Reset smooth running adaptations. Test drive the vehicle: if the high trim value and fault code shift to Cylinder 1 (P0263), the injector is defective. If the fault stays on Cylinder 2 (P0266), the issue is mechanical or valvetrain related.
Intake Port Endoscopy & Valvetrain Lift Measurement
If the injector is proven healthy and relative compression is borderline, remove the intake manifold and inspect Cylinder 2 intake port for severe EGR carbon restriction. Use a dial indicator on the Cylinder 2 valve spring retainers while turning the crankshaft manually to verify that cam lobe wear has not reduced valve lift compared to other cylinders.
Hårdvarureparation och stycklista för komponenter
Cylinder 2 Fuel Metering Calibration & IMA Coding Architecture
0 445 110 369 / 0 445 116 059
High-precision electro-hydraulic fuel injector with laser-etched IMA calibration classification code
F 00V C17 503 / OEM Copper Crush Washer
Gas-tight sealing ring preventing combustion gas leakage that drops effective cylinder compression
DLLA 150 P 1828 / OEM Nozzle Assembly
Atomizes high-pressure diesel into micro-droplets; clogged micro-holes reduce cylinder contribution
Interaktiv toleransberäknare för Common Rail
Tillhörande bränslesystemkomponenter
The following genuine OEM fuel pumps and common rail injectors are verified factory equipment for engines reporting fault protocol P0266. Cross-reference operating pressures and tightening torques before sub-assembly replacement:
0445110021BOSCH
BOSCH 0445110021 - F9Q 1.9 dCi Common Rail Injector
View Technical Specs & Fitment →0445110239BOSCH
0445110239 Injector: PSA 1.6 HDi Ford 1.6 TDCi Specs
View Technical Specs & Fitment →0445110369BOSCH
0445110369 Injector: VW 2.0 TDI EA189 CFFB CFHC Specs
View Technical Specs & Fitment →0445116024BOSCH
BOSCH 0445116024 Common Rail Piezo Injector for BMW N47 2.0d & N57 3.0d
View Technical Specs & Fitment →095000-5880Denso
095000-5880 Denso Toyota 2KD-FTV Injector: 23670-30050 Data
View Technical Specs & Fitment →28337917Delphi
28337917 Delphi Bobcat D24 Injector: 7030364 Specs & Data
View Technical Specs & Fitment →Återställning av pumpinläring och provkörning
Following injector replacement, cleaning, or valvetrain repair for P0266, perform the following ECM adaptation sequence:
1. In the scan tool, enter Engine Control Module -> Special Functions -> Injector IMA / QR Coding.
2. Input the exact alphanumeric calibration code printed on the top of the replacement Cylinder 2 injector.
3. Execute 'Reset Cylinder Smooth Running Adaptations' and 'Reset Mean Quantity Learning Values'.
4. Bring the engine to full operating temperature (coolant > 80°C).
5. Perform a learning road test: drive the vehicle in 4th/5th gear, accelerating to 80 km/h and allowing the vehicle to coast down to 30 km/h with foot completely off the accelerator pedal (fuel cutoff overrun). Repeat this deceleration sequence 6 times to allow the ECM to calibrate injector minimum drive pulse offsets.
Differentialdiagnos & Relaterade felkoder
Verkliga verkstadsfall
2016 Ford Transit Custom 2.0 EcoBlue (Panther)(139,000 km)
Vanliga tekniska frågor
Vad betyder felkoden P0266?
Felkod (DTC) P0266 indikerar att motorstyrenheten (ECM/PCM) har nått sitt maximala adaptiva bränslekompensationsgränsvärde för cylinder 2 i ett misslyckat försök att balansera motorns rotationshastighet och cylinderns effektutveckling. I moderna common rail-dieselsystem kör ECM kontinuerligt en funktion för jämn gång (Smooth Running Control) eller cylinderbalansering vid tomgång och jämn dellast. Genom att mäta variationer på mikrosekundnivå i vevaxelns acceleration mellan tändpulserna via vevaxelgivaren (CKP), trimmar ECM bränslemängden (mg/slag eller mm³/slag) dynamiskt per cylinder. Om cylinder 2 konsekvent levererar lägre vridmoment än snittet för övriga cylindrar - till följd av igensatta spridarmunstycken, internt läckage och för högt returflöde från reglerventilen, bristfällig kompression eller luftbrist - ökar ECM bränslemängden till cylinder 2. När detta korrigeringsvärde överskrider det övre kalibreringsgränsvärdet (vanligen +4.5 till +6.0 mg/slag) under en längre tid sätts P0266.
Vilka är de vanligaste symtomen på P0266?
Noticeable engine shudder, rough idling, and persistent vibration transmitting into cabin seats and steering wheel, Slight hesitation upon tip-in acceleration and uneven engine acoustics under steady-state cruising, Check Engine Light (MIL) illuminated with diagnostic trouble code P0266 stored in ECM memory, Puffs of greyish or black soot emitted from exhaust during low-speed maneuvering and takeoff, Gradual degradation in fuel economy due to uncoordinated and excessive cylinder trim enrichment, Live scan tool data shows Cylinder 2 Smooth Running Control value pegged at +4.5 to +6.0 mg/stroke (or -4.5 mg/stroke).
Vad orsakar P0266 på en dieselmotor?
Internal wear or carbon buildup on Cylinder 2 common rail fuel injector nozzle needle and spray holes; Excessive injector backleak (leak-off) from Cylinder 2 control valve reducing delivered fuel volume into the chamber; Mechanical compression deficiency in Cylinder 2 (worn piston rings, leaking intake/exhaust valve, or blown head gasket); Incorrect, unprogrammed, or corrupted IMA/QR calibration code entered in the ECM for Cylinder 2; Carbon sludge accumulation in the intake swirl port or runner dedicated to Cylinder 2; Damaged or worn hydraulic valve lifter, rocker arm, or camshaft lobe on Cylinder 2.
Är det säkert att köra med felkod P0266 aktiv?
🟡 Varning: Halta-hem-läge / Uppsök verkstad
Vad kostar det att åtgärda felkod P0266?
Typiska reparationskostnader för felkod P0266 beror på den bakomliggande orsaken och diagnostiknivån: Nivå 1 (Mindre underhåll / Gör-det-själv): 400 kr - 1 150 kr: Rengöring av bränslesystem och byte av bränslefilter (Rengöring av givare, bränslefilterbyte, säkringskontroll eller kontaktstiftsrengöring.); Nivå 2 (Komponentbyte): 1 900 kr - 5 000 kr: Byte av spridare cylinder 2 med Bosch/Denso-originaldel (Byte av enskild komponent (tryckreglerventil, doseringsventil eller renoverad spridare).); Nivå 3 (Större delsystem): 9 000 kr - 23 000 kr: Mekanisk kompressionsmätning eller reparation av topplock (Översyn av högtryckspump, ny OEM-spridaruppsättning eller byte av DPF-enhet.). Verkstadsriktpriser. Mer än 70 % av fallen åtgärdas inom nivå 1 eller 2 utan att hela delsystem behöver bytas.
What is the difference between DTC P0302 and DTC P0266?
P0302 is an active misfire code triggered when the crankshaft decelerates sharply during Cylinder 2's power stroke (combustion failure). P0266 is a fuel trim adaptation code triggered when the ECM has continuously adjusted Cylinder 2's fuel quantity to the absolute limit (+4.5 to +6.0 mg/stroke) in an attempt to balance idle speed, but the cylinder still contributes uneven torque.
Can bad fuel cause P0266 on only one cylinder?
Usually bad fuel affects all injectors. However, if water or fine particulates were present, the injector closest to the rail inlet or the injector with the smallest manufacturing tolerances may foul or experience valve scuffing first, leading to P0266 isolated to Cylinder 2.
Will reprogramming the IMA code fix P0266 if the injector is not replaced?
If an incorrect IMA code was previously entered (e.g., during previous repair), writing the correct code can resolve P0266. However, if the code already matches the injector head, P0266 indicates physical hydraulic wear or carbon clogging that cannot be solved by re-entering the existing code.