FuelPartsDB · WORKSHOP TECHNICAL SERVICE

DOC REF: SOP-CR-INJ-01

WORKSHOP INSTALLATION JOB SHEET & SOP

GM 12668635GM 12668635 SIDI Direct Fuel Injector Buick Enclave Chevrolet Blazer Traverse Cadillac XT6 3.6L V6 LGX · Euro 255

Technician / Installer:

Date / Odometer:

Vehicle Reg / VIN:

Quality Sign-off:

CRITICAL INSTALLATION SPECIFICATIONS & TORQUES

Torques (Hold-down):10 N·m

Torques (Tightening):25 N·m

Copper washer:Renew the sealing washer on every installation. 1.50 mm standard; step up to 1.70 mm after light seat reaming, 2.00 mm after heavy seat refinishing.

IMA / ECU coding:Not required for this assembly

MANDATORY INSTALLATION CHECKLIST

[ ]Bore cleaned to bare metal using nylon/brass reaming brush & vacuumed (zero debris / no steel wire)
[ ]New copper sealing washer fitted with correct thickness (do not reuse old washer)
[ ]High-temperature ceramic paste applied to injector body shaft (never coat the nozzle tip)
[ ]Hold-down clamp bolt tightened in stage torque/angle sequence as specified
[ ]Fuel rail high-pressure line union torqued without tension or cross-threading
[ ]IMA / QR calibration code entered into diagnostic tool (Lexia/KTS/VCDS) for cylinder balancing
[ ]Low-pressure air bleed performed, engine idling leak-off test verified leak-free

12668635

View Specs

SolenoidGasoline Direct Injection (GDI)Euro 255

GM 12668635 SIDI Direct Fuel Injector Buick Enclave Chevrolet Blazer Traverse Cadillac XT6 3.6L V6 LGX

Reference data for Bosch 12668635 common rail injector · OEM 12668636, 12684125, 12684126, 217-3445, FJ1296 · Application GM 3.6L High Feature V6 SIDI (LFX / LLT / LGX / LFY)

Engine Platform:GM 3.6L High Feature V6 SIDI (LFX / LLT / LGX / LFY) →

OE REFERENCE12668636, 12684125, 12684126, 217-3445, FJ1296

CONTROL VALVE-

NOZZLE-

RAIL PRESSURE150 bar

EMISSIONTier 2 Bin 5 / Euro 5 / LEV II

WARRANTY12 Months

Compatible Injectors

OEM Ref

Vehicle & Engine Fitment

Vehicle	Engine	Years
Chevrolet Camaro / Impala / Traverse	GM 3.6L High Feature V6 SIDI (LFX / LLT / LGX / LFY)	2012-2020
Cadillac CTS / ATS / SRX	GM 3.6L High Feature V6 SIDI (LFX / LLT / LGX / LFY)	2012-2016
GMC Acadia	GM 3.6L High Feature V6 SIDI (LFX / LLT / LGX / LFY)	2012-2016

Technical Specifications

Specification	Value
Part Number / SKU	12668635
Manufacturer Brand	GM
Component Type	Direct Fuel Injector
Engine Application	General Motors 3.6L V6 DOHC 24V SIDI Direct Injection with AFM (LGX / LFY)
Operating PressureCore Spec
Mounting Torque (Flange / Bracket)	10 N-m (89 lb-in)
Fuel Line / Rail Torque	25 N-m (18 lb-ft)
Primary Diagnostic Fault Codes	P0300, P0301, P0172, P0175

Installation Tips

Depressurize Fuel System: Pull fuel pump fuse or disconnect LPFP harness. Crank engine 5-8 seconds until it stalls to drop residual rail pressure below 5 bar.
Clean Surrounding Cavity: Blow compressed air around cylinder head bore or pump flange cavity to prevent dirt ingress into the fuel rail.
Lubricate & Fit Seals: Inspect Teflon combustion seals or O-rings. Coat lightly with clean motor oil (do not use grease) to avoid tearing during insertion.
Torque to Factory Specification: Hand-thread bolts evenly. Tighten mounting fasteners to 10 N-m (89 lb-in), and torque fuel line fittings to 25 N-m (18 lb-ft).
Prime & Leak Check: Cycle ignition to RUN position 3 times (5 seconds each) to build low-side pressure. Inspect fittings for leaks before starting engine.

Diagnostic Trouble Codes & Fault Protocols

Common diagnostic trouble codes (DTCs) triggered when this common rail injector experiences wear, circuit faults, or calibration drift:

P0087Critical

Fuel Rail / System Pressure Too Low

Excessive internal backleak from worn control valve seats drops common rail pressure below target under engine load.

P0087 Guide →🧪 Backleak Calculator

P0201 - P0208High

Injector Circuit Malfunction / Open Circuit

Solenoid coil resistance drift (0.2-0.5 Ω) or piezo stack degradation triggers driver stage shutdown on affected cylinders.

P0201 Circuit Guide →

P0300 / P0301+High

Cylinder Misfire & Balancing Deviation

Carbon-clogged nozzle spray holes or missing IMA calibration causes uneven cylinder contribution. Recode ECM and verify washer seating.

P0300 Misfire Protocol →💻 IMA Coding Tool 📐 Washer Thickness

P0088High

Fuel Rail / System Pressure Too High

Spill line backpressure or stuck metering valve prevents rail depressurization, creating overpressure risks under load.

P0088 Guide →📊 Rail Pressure Converter

Browse all 61 Diesel Diagnostic Trouble Codes in our Workshop Hub ->

WORKSHOP PROTOCOLS

Technical Diagnostic & Service Protocols

Authoritative field procedures, diagnostic testing thresholds, and service SOPs for this assembly.

COMMON RAIL WORKSHOP DIAGNOSTICS

Fuel Metering Valve (IMV/SCV) Diagnostics Guide

Diagnostic guide for common rail fuel metering valves (IMV/SCV/FCA/MPROP). Normally open vs closed, coil resistance, PWM duty cycle & P0088 / P0089 test.

Read Technical Protocol

OBD-II DIAGNOSTIC PROTOCOL

P0087 Low Rail Pressure Diagnosis Guide

Step-by-step workshop diagnostic protocol for OBD-II DTC P0087 (Fuel Rail Pressure Too Low). 5-stage troubleshooting tree: backleak testing, SCV valve, PRV valve, and high-pressure pump.

Read Technical Protocol

DIESEL WORKSHOP DIAGNOSTIC SOP

Cylinder Balance & Injector Deviation Guide

Common rail diesel cylinder balance & smooth running diagnostic guide. Balance rates, mg/stroke deviation, P0263 misfire, compression vs injector test.

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ASSEMBLY & INSTALLATION PROTOCOL

Diesel Injector Torque Specs & TTY Angles Guide

Common rail diesel injector hold-down bolt torque specs, TTY angles & pipe unions. Covers Bosch, Detroit DD13, Cummins & VAG 2.0 TDI workshop data in Nm.

Read Technical Protocol