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OBD-II DİZEL ATÖLYE PROTOKOLÜ8-10 min read
P0671Kızdırma BujisiOrta Önem💡 Motor Arıza Lambası Yanıyor

P0671: Silindir 1 Kızdırma Bujisi Devresi / Açık Devre

FuelPartsDB Teknik Mühendislik EkibiYayınlanma: Son Güncelleme: Uzmanlık: Common Rail Sistemleri

Arıza Teşhis Kodu (DTC) P0671; Motor Kontrol Ünitesinin (ECM/PCM) veya elektronik Kızdırma Bujisi Kontrol Ünitesinin (GCU), doğrudan Silindir 1 kızdırma bujisi devresinde elektriksel bir açık devre, aşırı yüksek direnç veya iletim kopukluğu tespit ettiğini gösterir. Modern ortak hatlı (common rail) dizel motorlarda her bir kızdırma bujisi, elektronik kontrol ünitesi tarafından bağımsız olarak tetiklenen ve denetlenen bir akım hattı üzerinden beslenir. Ön ısıtma ve son ısıtma (post-heating) evrelerinde, Silindir 1 hattına atanmış dahili akım algılama şönt direnci üzerinden geçen akımın buji enerjilendiğinde sıfıra yakın olduğunu (< 1.0 A) saptar. Bu durum, Silindir 1 kızdırma bujisinin dahili ısıtma filamanının yandığını (koptuğunu), buji soket başlığının yerinden çıktığını veya kablo demetinde bir kopukluk meydana geldiğini gösterir.

🚗 SÜRÜCÜ REHBERİ VE ONARIM PROTOKOLÜ

🚗 Sürüş Güvenliği, Tahmini Onarım Maliyeti ve Doğrulama

🟢 Bilgi: Sürüşe Uygun / Emisyon Kontrolü
  1. 01

    🚦 Sürüş Güvenliği ve Mekanik Risk

    Acil mekanik değerlendirme ve çekici gereksinimi

    Silindir 1 Kızdırma Bujisi Devresi Açık - Soğuk Çalıştırma Güçlüğü ve DPF Rejenerasyon Engeli

    Silindir 1 kızdırma bujisinin ısıtma elemanı açık devre yapmıştır (yanmıştır). Sıcak havalarda motor çalışsa bile soğuk ilk çalıştırmada tekleme ve beyaz duman meydana gelir. En kritik nokta ise ECU'nun aktif DPF rejenerasyon döngülerini askıya alacak olmasıdır.

    SÜRÜŞE DEVAM EDİLMESİ DURUMUNDA MOTOR RİSKLERİ:Askıya alınan DPF rejenerasyonları aşırı kurum birikimine (P2463) ve nihayetinde yüksek maliyetli DPF değişimine yol açar.
  2. 02

    💰 Servis Onarım Bütçesi

    Beklenen parça değişimi ve servis işçilik maliyet kademeleri
    Küçük Bakım / Filtre Temizliği750 ₺ - 1.800 ₺: Silindir 1 Kızdırma Bujisinin Bosch/NGK/BERU Parçası ile Kendin Yap (DIY) Değişimi

    Sensör temizliği, yakıt filtresi değişimi, sigorta kontrolü veya kablo soketi temizliği.

    Valf / Sensör Değişimi2.700 ₺ - 6.600 ₺: Zincirleme Arızaları Önlemek İçin 4 Kızdırma Bujisinin Birden Değişimi

    Tek bileşen değişimi (basınç regülatörü, dozaj valfi veya revizyonlu enjektör).

    Ağır Onarım / Pompa ve Enjektörler10.500 ₺ - 25.500 ₺: Silindir Kapağında Kaynayan/Kırılan Kızdırma Bujisini Özel Takımla Çıkarma İşçiliği

    Yüksek basınç pompası revizyonu, yeni OEM enjektör takımı veya DPF değişimi.

    Servis referans fiyatları. Arızaların %70'inden fazlası komple parçalar değiştirilmeden Seviye 1 veya 2 dahilinde çözülür.

  4. 03

    🧰 Hızlı Görsel ve Fiziksel Kontroller

    Servisi aramadan önce aletsiz 5 dakikalık hızlı kontrol
    11. Multimetre ile direnç ölçün: Silindir 1 kızdırma bujisinin başlığını sökün, bir probu orta terminale ve diğerini motor gövdesi şasisine değdirin (sağlam buji: 0,6 - 1,5 Ohm; yanık buji: sonsuz / OL).
    22. Asla soğuk motorda sökmeye çalışmayın: Motoru daima 80 °C'ye kadar ısıtın ve 24 saat önceden nüfuz edici pas sökücü uygulayın.
    33. Tork sınırına uyun: Buji ucunun kırılmasını önlemek için sökme işlemi sırasında 25-30 N-m kırılma torkunu aşmayın.
  5. 04

    🛡️ Yanıltıcı Arıza Teşhisine Karşı Koruma

    Gereksiz parça değişimini önlemek için tamirciye sorulacak sorular
    ""Kızdırma bujisi kontrol modülünü değiştirmeden önce lütfen ohmmetre ile Silindir 1 kızdırma bujisinin direncini doğrulayın.""
    ""Yeni buji dişlerine mutlaka yüksek sıcaklık seramik montaj pastası uygulayın ve üretici standardı olan 10-15 N-m torkla sıkın.""
    ""Kızdırma bujisi arıza kodunu sildikten sonra DPF rejenerasyon durumunun normale döndüğünü kontrol edin.""

    Teknik Not: Yüksek maliyetli parça değişimini onaylamadan önce ustanıza bu soruları yöneltin:

🔧 UZMAN TEKNİSYEN TAVSİYESİ VE ONARIM PROTOKOLÜRAPID ASSESSMENT

30 Saniyelik Hızlı Atölye Triyajı

Temel Belirtiler
  • Check Engine Light (MIL) and amber spiral glow plug indicator illuminated on the dashboard
  • Engine stumbling, rough idle, and misfiring on Cylinder 1 for 15-45 seconds following a cold start
  • Puffs of unburned white or grey exhaust smoke during cold starting with a strong smell of raw diesel fuel
En Olası Nedenler
  • Burned out, fractured, or open internal heating filament inside the Cylinder 1 glow plug
  • Loose, disconnected, or corroded electrical connector cap on the Cylinder 1 glow plug terminal
  • Broken, chafed, or melted wiring harness wire between the Glow Control Unit and Cylinder 1 glow plug
İlk Gerekli İşlem

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.

🛠️ Geri Dönüş (Back-Leak) Denge Analizörü

Expensive Diagnostic Pitfall & Technical Reality

❌ Yaygın servis yanılgısı:

P0671 requires replacing all 4/6 glow plugs immediately, and if plug 1 is seized in the head, the entire cylinder head must be removed ($1,200 - $2,500).

🔍 Teknik ve hidrolik gerçeklik:

P0671 is an isolated circuit fault specific to Cylinder 1. It means the glow plug control module measured infinite resistance (open circuit) on Cylinder 1's heater circuit. In over 85% of cases, the other cylinders' glow plugs are completely healthy and should NOT be disturbed (unnecessarily disturbing healthy plugs risks shearing them in the head). The root cause is a burned-out heating element inside plug 1 or a loose push-on connector boot that has vibrated off.

💡 Teknik doğrulama protokolü:

Risking head removal and high-cost glow plug extraction ($1,500+) by forcing all plugs out vs testing plug 1 with a $15 multimeter and replacing only the single $18-$35 plug with proper vibration-warm extraction technique, saving over $1,400.

Glow Plug Tip Swelling & Thread Shearing Catastrophe Warning

CRITICAL WORKSHOP WARNING: Extreme care is mandatory when removing the Cylinder 1 glow plug to prevent cylinder head destruction!

MANDATORY PROTOCOL: When a glow plug fails, electrical arcing or combustion oil contamination often causes the heating tip to swell in diameter. When unscrewing the plug, the swollen tip can jam in the cylinder head bore. NEVER force the plug with an impact wrench! Apply penetrating oil, run the engine to full operating temperature (90°C), and use a calibrated torque wrench set to a maximum of 25 Nm (M8) or 35 Nm (M10). If the plug binds, work it back and forth with penetrating fluid to avoid snapping the plug inside the cylinder head.

PLATFORM ARCHITECTURE

En Çok Etkilenen Motorlar ve Enjeksiyon Sistemleri

Bu arıza kodu öncelikle aşağıdaki common rail dizel platformlarını etkiler. Fabrika arıza modelleri ve parça numaraları için motor ailenizi inceleyin:

Volkswagen / Audi 2.0 TDI (EA189 / CFFB / CFGB)

Bosch EDC17 Common Rail System

Bilinen Fabrika Arıza Modeli: Piezo stack degradation, injector harness terminal fretting, DPF differential pressure sensor silicone tube split.

Temel Alt Parça:03L130277, 0445110369, 076906051A
Volkswagen / Audi 2.0 TDI (EA189 / CFFB / CFGB) Motor Teknik Merkezini İncele →

Renault / Opel 1.9 dCi (F9Q)

Bosch EDC15 / EDC16 Common Rail System

Bilinen Fabrika Arıza Modeli: Injector harness connector diesel seepage, glow plug tip carbon seizure, EGR valve soot accumulation.

Temel Alt Parça:7700107165, 0445110021, 8200542997
Renault / Opel 1.9 dCi (F9Q) Motor Teknik Merkezini İncele →

BMW 2.0d / 3.0d (N47 / N57 / M57TU2)

Bosch CRI2.5 / CRI3.0 Common Rail

Bilinen Fabrika Arıza Modeli: Injector balance drift beyond +/- 4.0 mg/stroke, glow plug control unit (BERU) power lead failure, DPF backpressure accumulation.

Temel Alt Parça:13537805428, 0445116024, 12217801201
BMW 2.0d / 3.0d (N47 / N57 / M57TU2) Motor Teknik Merkezini İncele →

Ford / PSA 1.6 TDCi / HDi (DV6ATED4 / DLD-416)

Bosch CRI2-16 Common Rail System

Bilinen Fabrika Arıza Modeli: Injector copper washer blow-by (black death), injector cylinder circuit fretting corrosion, DPF pressure pipes heat cracking.

Temel Alt Parça:0445110239, 1980J7, 1618LP
Ford / PSA 1.6 TDCi / HDi (DV6ATED4 / DLD-416) Motor Teknik Merkezini İncele →
WORKSHOP MASTER TEARDOWN GUIDE

Diesel Glow Plug Diagnostics & Circuit Troubleshooting Guide

Workshop troubleshooting guide for diesel glow plug fault codes P0380, P0670, and P0671 to P0674. Resistance specs, GPCM relay testing, and removal torque.

Read Full Master Guide →
THEORY OF OPERATION

Kontrol Devresi ve Aktüatör Çalışma Mantığı

1. Dynamic In-Demand Fuel Metering

The Cylinder 1 glow plug is threaded directly into the cylinder head with its heating tip protruding into the combustion chamber adjacent to the common rail fuel injector nozzle. It receives current via a dedicated wire running from Channel 1 of the Glow Control Unit. The outer steel casing of the glow plug provides the electrical ground return through its threads directly into the engine block. When energized, current flows through an internal heating and regulating coil, heating the tip to over 1,000°C in under 2 to 4 seconds.

2. Closed-Loop PID Deviation Monitoring

The GCU's internal microprocessor monitors instantaneous current on the Cylinder 1 output MOSFET on every activation cycle. Under normal conditions, inrush current peaks at 15A-25A and stabilizes at 8A-12A. If current fails to exceed 1.0 A within 200 milliseconds of activation (indicating infinite resistance / open circuit), the GCU registers a Channel 1 fault and transmits this status to the ECM over the LIN-bus, setting DTC P0671 and turning on the glow plug warning light.

3. Diagnostic Trap: Normally Open (NO) vs Normally Closed (NC) Valves

Open Circuit Isolation Rule: An open circuit on Cylinder 1 glow plug causes cold-start stumbling and white smoke isolated to Cylinder 1. Once the engine warms up, the fault disappears from driveability, but the DTC remains stored in the ECM. The most common cause is a burned-out heating filament inside the plug, which can be verified in under 60 seconds with an ohmmeter.

ENGINEERING SPECIFICATIONS

Elektriksel ve Hidrolik Fiziksel Standartlar

Solenoid Coil DC ResistanceStandard 12V Metal Glow Plug: 0.6 - 1.2 Ω @ 20°C; Low-Voltage Ceramic Plug: 0.3 - 0.5 Ω; Open Circuit: > 10 Ω (OL)Measured @ 20°C across terminals 1 & 2
Insulation Resistance> 10 MΩ measured between glow plug terminal pin and outer threaded body (tested @ 250V/500V DC)Between terminals and pump body (ground)
Operating Supply VoltagePulsed DC Voltage: 4.4 V to 11.5 V DC depending on engine design; Battery supply > 12.0 VHigh-side feed from ECM / main relay
PWM Frequency StandardPulse-Width Modulated (PWM) current feed controlled by electronic GCUSquare-wave PWM modulation
Idle Duty Cycle (Warm Engine)Pre-heating Phase Current: 15 A - 25 A inrush decaying to 8 A - 12 A holding current per plugNominal baseline at 250–350 bar
Full-Load Duty Cycle (WOT)Threshold for DTC P0671 (Open Circuit): Current draw < 1.0 A during commanded activationMaximum high-speed fuel delivery demand
Low-Pressure Feed SupplyMaximum Permissible Harness Resistance: < 0.3 Ω from GCU output pin to Cylinder 1 glow plug terminalMeasured at pump fuel inlet
Internal Cascade BackpressureMaximum Breakaway Shear Torque: M8 threads = 20-25 Nm; M10 threads = 35-40 Nm (never exceed to prevent snapping!)Controlled by overflow cascade valve
PROCEDURAL PROTOCOL

Adım Adım Atölye Teşhis Protokolü

STEP 1

Measure Cylinder 1 Glow Plug Resistance In-Place

Turn ignition OFF and pull the electrical connector cap off the Cylinder 1 glow plug. Set a digital multimeter to the lowest resistance scale (200 Ω) and zero the test leads. Touch one probe to the glow plug center terminal pin and the other probe to clean metal on the cylinder head. A healthy standard plug reads 0.6-1.2 Ω (low-voltage ceramic reads 0.3-0.5 Ω). An infinite reading (OL / > 10 Ω) confirms that the glow plug filament is burned open and must be replaced.

STEP 2

Test Harness Voltage Output from Glow Control Unit

Connect a 12V test light (or digital multimeter) between the Cylinder 1 glow plug harness cap and cylinder head ground. Turn ignition ON with a cold engine. The test light must illuminate brightly (or multimeter show battery voltage / PWM pulse) for 2 to 5 seconds. If power is present at the cap but the plug is open, replacing the plug resolves the issue.

STEP 3

Harness Continuity & Load Test to GCU

If no voltage was measured at the harness cap, disconnect the output connector at the Glow Control Unit. Using a digital multimeter, test continuity on the wire from the GCU Channel 1 pin to the Cylinder 1 glow plug connector (must read < 0.3 Ω). Perform a dynamic load test using a 21W automotive bulb to verify that the wire can support current without high-resistance voltage drops.

STEP 4

Test Glow Plug Terminal Ground Path Through Cylinder Head

Measure resistance between the outer hexagonal steel body of the glow plug and the battery negative terminal. Resistance must be < 0.1 Ω. If excessive resistance is found, corrosion or thread sealant on the glow plug threads is preventing electrical ground return.

STEP 5

Safe Removal & Torque Limit Inspection

If replacing the plug, warm the engine to operating temperature (> 80°C). Spray high-grade penetrating fluid around the glow plug base. Use a calibrated torque wrench set to 20 Nm (M8) or 35 Nm (M10). Gently apply counter-clockwise pressure. If the plug turns freely, remove it; if it binds, turn it back clockwise slightly and re-apply penetrating fluid to work carbon out of the threads.

STEP 6

New Glow Plug Installation & Thread Preparation

Before installing a new glow plug, ream the carbon out of the glow plug aperture using an OEM reamer tool greased to catch carbon flakes. Apply a tiny smear of high-temperature ceramic anti-seize paste to the threads (avoiding the heating tip). Tighten to specified factory torque (typically 12-15 Nm for M8, 15-20 Nm for M10).

COMPONENT-LEVEL REPAIR

Donanım Onarımı ve Yedek Parça Listesi (BOM)

Cylinder 1 Cold-Start Preheating Subsystem

Bosch Duraterm High-Efficiency Glow Plug - Cylinder 1

0 250 403 008 / Beru GE101 / OEM Glow Plug

Reaches 1,000°C tip temperature within 3 seconds to facilitate compression ignition

OEM: Protocol: Check resistance with digital multimeter: normal is 0.5 - 1.2 ohms; replace if open circuit (>10 ohms)
Glow Plug Wiring Harness Single-Terminal Push-On Boot

OEM Silicone Glow Cap Wire Repair Pigtail

Provides corrosion-resistant high-current contact to the glow plug terminal pin

OEM: Protocol: Replace if silicone boot is hardened, cracked, or loose on the plug tip
High-Temperature Ceramic Assembly Paste (Metal-Free)

Beru GKF01 / Liqui Moly 3418 Ceramic Paste

Prevents galvanic corrosion and thread seizure between glow plug steel threads and aluminum cylinder head

OEM: Protocol: Mandatory application to threads and shaft during installation
Workshop Technical & Economic Benchmark: Installation torque: 15 - 18 Nm; Breakaway torque limit: 35 Nm (NEVER exceed 35 Nm to avoid shearing the plug); Long-reach thin-wall 8mm/10mm glow plug socket.
LIVE WORKSHOP TOOL

Canlı Common Rail Tolerans Hesaplayıcı

Glow Plug Resistance & Current Draw Inspector

Test resistance across glow plug terminal to cylinder head ground: Healthy plugs read 0.5 - 1.2 ohms. If reading OL (infinity), the internal heater filament is severed.

📐 Factory Engineering Tolerance: Normal Glow Plug Resistance: 0.5 - 1.2 Ohms (Cold)
Launch Dedicated Calculator with Factory Tolerances →
OEM REPLACEMENTS

İlgili Common Rail Parçaları

The following genuine OEM fuel pumps and common rail injectors are verified factory equipment for engines reporting fault protocol P0671. Cross-reference operating pressures and tightening torques before sub-assembly replacement:

Common Rail Injector

0445110021BOSCH

BOSCH 0445110021 - F9Q 1.9 dCi Common Rail Injector

View Technical Specs & Fitment →
Common Rail Injector

0445110239BOSCH

0445110239 Injector: PSA 1.6 HDi Ford 1.6 TDCi Specs

View Technical Specs & Fitment →
Common Rail Injector

0445110369BOSCH

0445110369 Injector: VW 2.0 TDI EA189 CFFB CFHC Specs

View Technical Specs & Fitment →
Common Rail Injector

0445116024BOSCH

BOSCH 0445116024 Common Rail Piezo Injector for BMW N47 2.0d & N57 3.0d

View Technical Specs & Fitment →
CALIBRATION RELEARN

Yüksek Basınç Pompası Adaptasyon Sıfırlama ve Test

Following the replacement of the Cylinder 1 glow plug or harness repair for DTC P0671:

1. Clear all stored trouble codes from the Engine Control Module using an OBD-II diagnostic tool.

2. Access ECM Special Functions -> 'Glow Plug Adaptation / Reset Learned Resistance' (if required on vehicle platform).

3. Switch ignition OFF and leave undisturbed for 30 seconds to allow the ECM and GCU to register the cleared fault status.

4. Perform a cold soak test: let the engine cool, switch ignition ON, and verify that the spiral glow light illuminates and turns off normally.

5. Start the engine and verify smooth combustion on Cylinder 1 without cold-start shaking or white smoke.

DIFFERENTIAL DIAGNOSIS

Diferansiyel Teşhis ve İlgili Hata Kodları

P0672

Cylinder 2 Glow Plug Circuit / Open

P0670

Glow Plug Module Control Circuit / Open

P0301

Cylinder 1 Misfire Detected

P0380

Glow Plug/Heater Circuit 'A' Malfunction

FIELD REPAIR REPORTS

Atölye Saha Vaka İncelemeleri

CASE #1

2015 Volkswagen Golf 1.6 TDI (EA288 CLHA)(168,000 km)

Reported Complaint:Prolonged cold morning cranking (5 seconds) with cloud of white exhaust smoke on startup; yellow check engine light with P0671.
Teardown Root Cause:Multimeter resistance test: Cylinder 1 glow plug read OL (open circuit infinity), while Cylinders 2, 3, and 4 read 0.8 Ohms (perfect).
Repair Solution:Warmed engine to 80°C, applied penetrant oil, set torque wrench limit to 30 Nm, and smoothly unthreaded plug 1 without binding. Installed replacement Bosch plug with Beru ceramic paste, torqued to 15 Nm. Sub-zero cold start was instantaneous with P0671 resolved.
DIAGNOSTIC FAQ

Sıkça Sorulan Teknik Sorular

P0671 motor arıza kodu ne anlama gelir?

Arıza Teşhis Kodu (DTC) P0671; Motor Kontrol Ünitesinin (ECM/PCM) veya elektronik Kızdırma Bujisi Kontrol Ünitesinin (GCU), doğrudan Silindir 1 kızdırma bujisi devresinde elektriksel bir açık devre, aşırı yüksek direnç veya iletim kopukluğu tespit ettiğini gösterir. Modern ortak hatlı (common rail) dizel motorlarda her bir kızdırma bujisi, elektronik kontrol ünitesi tarafından bağımsız olarak tetiklenen ve denetlenen bir akım hattı üzerinden beslenir. Ön ısıtma ve son ısıtma (post-heating) evrelerinde, Silindir 1 hattına atanmış dahili akım algılama şönt direnci üzerinden geçen akımın buji enerjilendiğinde sıfıra yakın olduğunu (< 1.0 A) saptar. Bu durum, Silindir 1 kızdırma bujisinin dahili ısıtma filamanının yandığını (koptuğunu), buji soket başlığının yerinden çıktığını veya kablo demetinde bir kopukluk meydana geldiğini gösterir.

P0671 kodunun en yaygın belirtileri nelerdir?

Check Engine Light (MIL) and amber spiral glow plug indicator illuminated on the dashboard, Engine stumbling, rough idle, and misfiring on Cylinder 1 for 15-45 seconds following a cold start, Puffs of unburned white or grey exhaust smoke during cold starting with a strong smell of raw diesel fuel, Slightly longer cranking time before the engine fires up when temperatures are near or below freezing, Active DPF soot regeneration blocked on some vehicle platforms, leading to eventual soot accumulation, Diagnostic scan tool reports 'Cylinder 1 Glow Plug Circuit Open / Electrical Malfunction'.

Dizel motorda P0671 arızasına ne sebep olur?

Burned out, fractured, or open internal heating filament inside the Cylinder 1 glow plug; Loose, disconnected, or corroded electrical connector cap on the Cylinder 1 glow plug terminal; Broken, chafed, or melted wiring harness wire between the Glow Control Unit and Cylinder 1 glow plug; Blown internal output driver MOSFET channel for Cylinder 1 inside the Glow Control Unit (GCU); Severe carbon buildup or corrosion on the glow plug threads preventing adequate electrical grounding to the cylinder head; Water intrusion in the glow plug harness boots causing terminal pin oxidation and contact loss.

P0671 kodu etkinken araç sürmek güvenli midir?

🟡 Dikkat: Koruma Modu Aktif / Servise Gidin

P0671 arıza kodunun tamir maliyeti ne kadardır?

P0671 arıza kodu için tipik onarım maliyetleri kök nedene ve teşhis seviyesine bağlıdır: Seviye 1 (Hafif Onarım / Bakım): 750 ₺ - 1.800 ₺: Silindir 1 Kızdırma Bujisinin Bosch/NGK/BERU Parçası ile Kendin Yap (DIY) Değişimi (Sensör temizliği, yakıt filtresi değişimi, sigorta kontrolü veya kablo soketi temizliği.); Seviye 2 (Parça Değişimi): 2.700 ₺ - 6.600 ₺: Zincirleme Arızaları Önlemek İçin 4 Kızdırma Bujisinin Birden Değişimi (Tek bileşen değişimi (basınç regülatörü, dozaj valfi veya revizyonlu enjektör).); Seviye 3 (Komple Revizyon): 10.500 ₺ - 25.500 ₺: Silindir Kapağında Kaynayan/Kırılan Kızdırma Bujisini Özel Takımla Çıkarma İşçiliği (Yüksek basınç pompası revizyonu, yeni OEM enjektör takımı veya DPF değişimi.). Servis referans fiyatları. Arızaların %70'inden fazlası komple parçalar değiştirilmeden Seviye 1 veya 2 dahilinde çözülür.

Can I continue driving with DTC P0671 active?

Yes, once the engine is warm, the glow plug plays no role in normal combustion, so the vehicle will drive with normal power and economy. However, in cold weather, the engine will start hard with Cylinder 1 misfiring and smoking. Additionally, some vehicles disable DPF regeneration while any glow plug code is active, which will eventually clog the DPF.

Should I replace all glow plugs when only Cylinder 1 has code P0671?

Yes, strongly recommended. All glow plugs endure the exact same number of thermal cycles, cold starts, and combustion exposures. When one plug burns open, the remaining plugs are usually near the end of their operational lifespan.

Can I test the glow plug without removing it from the engine?

Yes! Simply unplug the wiring cap from the top of the Cylinder 1 glow plug. Use a digital multimeter on the 200 Ω scale: place the positive probe on the center terminal pin and the negative probe on the engine cylinder head metal. If it reads OL (infinite resistance), the plug is 100% burned out and must be replaced.