FuelPartsDB · WORKSHOP TECHNICAL SERVICE

DOC REF: SOP-CR-INJ-01

WORKSHOP INSTALLATION JOB SHEET & SOP

HITACHI 079127025AFHITACHI 079127025AF High Pressure Fuel Pump Audi RS4 RS5 S6 S7 S8 A8 4.0T 4.2L V8 FSI HPP0017 · Euro 56

Technician / Installer:

Date / Odometer:

Vehicle Reg / VIN:

Quality Sign-off:

CRITICAL INSTALLATION SPECIFICATIONS & TORQUES

Torques (Hold-down):20 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

HITACHI

079127025AF

View Specs

SolenoidGasoline Direct Injection (GDI)Euro 56

HITACHI 079127025AF High Pressure Fuel Pump Audi RS4 RS5 S6 S7 S8 A8 4.0T 4.2L V8 FSI HPP0017

Reference data for Bosch 079127025AF common rail injector · OEM 079127025C, 0261520262, HPP0017 · Application Audi 4.0L TFSI & 4.2L FSI DOHC 32V V8 (EA824 / CEUC / CTGE / BNS)

Engine Platform:Audi 4.0L TFSI & 4.2L FSI DOHC 32V V8 (EA824 / CEUC / CTGE / BNS) →

OE REFERENCE079127025C, 0261520262, HPP0017

CONTROL VALVE-

NOZZLE-

RAIL PRESSURE120 bar

EMISSIONEuro 5 / Euro 6

WARRANTY12 Months

Compatible Injectors

OEM Ref

Vehicle & Engine Fitment

Vehicle	Engine	Years
Audi RS4 B7 / RS5 B8 / R8 4.2 FSI	4.2L V8 FSI DOHC 32V (BNS / CFSA)	2006-2015
Audi S6 C7 / S7 C7 / RS6 / RS7 4.0 TFSI	4.0L V8 Twin-Turbo TFSI (EA824 / CEUC / CRDB)	2012-2018
Audi A8 D4 / S8 D4 4.0 TFSI	4.0L V8 BiTurbo TFSI (CEUA / CTGA / DDTA)	2012-2018

Technical Specifications

Specification	Value
Part Number / SKU	079127025AF
Manufacturer Brand	HITACHI
Component Type	Mechanical High Pressure Fuel Pump (HPFP)
Engine Application	Audi 4.0L TFSI & 4.2L FSI DOHC 32V V8 (EA824 / CEUC / CTGE / BNS)
Operating PressureCore Spec
Mounting Torque (Flange / Bracket)	20 N-m (15 lb-ft)
Fuel Line / Rail Torque	25 N-m (18 lb-ft)
Primary Diagnostic Fault Codes	P0087, P0088, P0171, P2293

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 20 N-m (15 lb-ft), 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

Common Rail High-Pressure Pump Diagnostics Guide

Diagnose common rail high-pressure pump failure: suction vacuum, CP4 roller glitter, plunger wear, air ingress & P0087 hard start. Workshop bench testing.

Read Technical Protocol

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

COMMON RAIL WORKSHOP DIAGNOSTICS

Rail Pressure Relief Valve Diagnostics Guide

Common rail pressure relief valve (PRV) testing guide. Diagnose hot start stalls, P0087 rail pressure loss, return line leakage & single vs 2-stage valves.

Read Technical Protocol