02 27-16

1

02 27-16

SUBJECT

DATE

SPN 520268 (MCM) (GHG17)

February 2016

Additions, Revisions, or Updates
Publication Number / Title
DDC-SVC-MAN-0191

Platform

Section Title

Change

DD Platform
- GHG17

SPN 520268/FMI 18 GHG17

Remove obsolete information.

All information subject to change without notice.

02 27-16

Copyright © 2016 DETROIT DIESEL CORPORATION

3

2 SPN 520268/FMI 18 - GHG17

2

SPN 520268/FMI 18 - GHG17

Fuel Rail Pressure Too High, Similar Condition
Table 1.
SPN 520268/FMI 18
Description

Fuel Rail Pressure High

Monitored Parameter

Fuel Rail Pressure

Typical Enabling Conditions

Closed Loop & Actual Rail Pressure 200 Bar (2900 psi) Higher than
Desired Rail Pressure

Monitor Sequence

None

Execution Frequency

Continuous When Enabling Conditions Met

Typical Duration

Eight Seconds

Dash Lamps

MIL

Engine Reaction

None

Verification

Steady Engine rpm 1400 to 1500 (Two Minutes)

This fault can occur due to the conditions listed below:
Intermittent Loss of Engine Speed Signal
High Pressure Pump Internal Failure
Fuel Contamination
Rail Pressure Sensor
Motor Control Module (MCM)

•
•
•
•
•

Table 2.
Service Tools Used in the Procedure
Tool Number

Description

J-48876

Test Gauge, Primer Port, HDE

J-48704

Caps, HP Fuel Rail, HDE

J-48706
DiagnosticLink

Fuel Diagnostics Gauge Set LP, HDE
®

Standard

Check as follows:
WARNING: PERSONAL INJURY
Diesel engine exhaust and some of its constituents are known to the State of California to cause
cancer, birth defects, and other reproductive harm.
• Always start and operate an engine in a well ventilated area.
• If operating an engine in an enclosed area, vent the exhaust to the outside.
• Do not modify or tamper with the exhaust system or emission control system.
1. Did SPN 157/FMI 16 or SPN 520268/FMI 18 appear after the fuel system was repaired or fuel filter maintenance was
performed?
a. Yes; the code may be set due to air in the fuel system. Clear codes and road test to verify complaint. If code does
not set, release the vehicle. If code sets, Go to step 2.
b. No; Go to step 2.
2. Turn the ignition ON (key ON, engine OFF).
3. Check and record fuel level using parameter AS044 Fuel Tank Level. Is the fuel level under ¼ tank (25%)?
4

All information subject to change without notice.

Copyright © 2016 DETROIT DIESEL CORPORATION

02 27-16

02 27-16

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

a. Yes; add fuel and road test vehicle. If code does not become active during road test, release the truck. If the code
becomes active during the road test with over ¼ tank (25%) of fuel, Go to step 5.
b. No; Go to step 4.
Check fuel tank level in extended fault code data. Was fuel tank level over ¼ tank (25%) when the code logged?
a. Yes; Go to step 5.
b. No; fuel sloshing in the tank may have caused aerated fuel and set this code. Road test vehicle, if code does not
come active during road test, release the truck. If code does come active, Go to step 5.
Check for fuel contamination, including Diesel Exhaust Fluid (DEF), water, gasoline, kerosene, or coolant. Is any
contamination found?
a. Yes; refer to section "Contaminated Fluids" in this manual.
b. No; Go to step 6.
Using DiagnosticLink 8.03 or higher, check for other active codes. Are any of the following codes active?
a. Yes; perform the associated diagnostics first:
• SPN 157/FMI 1 Rail Pressure Too High
• SPN 164/FMI (All) Rail Pressure Sensor Faults
• SPN 174/FMI 0 Fuel Temperature Too High
• SPN 723/FMI (All) Cam Sensor Codes
• SPN 636/FMI (All) Crank Sensor Codes
• SPN 1077/FMI 5, 6
b. No; only SPN 1077/7, 157/16 or 1077/31 is present. Go to step 7.
Perform Automatic Fuel System Integrity Check (FSIC) routine using DiagnosticLink 8.03 or higher. With key ON,
Engine OFF, start the Automatic FSIC. The software/tool will ask to start the engine when required. Once the engine is
running, the software will have the engine enter and exit several engine operating conditions. Once the engine shuts
down, leave the key on for five minutes. Disconnect DiagnosticLink and open the log file. The next steps of the
troubleshooting will require reviewing the FSIC log file. Go to step 8.
Does Kw/Nw show/stay "ON / Enabled / True" while the engine is running during the Automatic FSIC routine?
a. Yes; Go to step 9.
b. No; refer to troubleshooting for SPN 723/FMI 10.
Was the fuel temperature rise greater than 5.6°C (10°F)?
a. Yes; Go to step 11.
b. No; Go to step 10.
At 600 rpm, is ASL003 Fuel Compensation Pressure between 586 kPa (85 psi) and 689 kPa(100 psi)?
a. Yes; Go to step 12.
b. No; Go to step 11.
Monitor AS124 LPPO sensor (if equipped) or use manual gauge J-48706. Is the pressure between 496 kPa (72 psi) and
551 kPa (80 psi) at 600 rpm and 689 kPa (100 psi) to 869 kPa (126 psi) at 1800 rpm?
a. Yes; Go to step 12.
b. No; repair cause of incorrect fuel pressure.
Monitor AS124 LPPO (if equipped) and ASL003 Fuel Compensation Pressure at all engine speeds, are pressures stable
with no oscillations? Unstable pressures will have oscillations greater than 10.3 kPa (1.5 psi) at stable engine speed.
a. Yes; Go to step 13.
b. No; Refer to section "Aerated Fuel Test – Two-Filter Fuel System".
Is ASL001 Rail Pressure erratic or have a saw tooth pattern?

All information subject to change without notice.

02 27-16

Copyright © 2016 DETROIT DIESEL CORPORATION

5

2 SPN 520268/FMI 18 - GHG17

a. Yes; Go to step 14.
NOTE: See examples of erratic pressure showing (1) ASL001 Rail pressure and (2) AS098 Desired rail pressure.
b. No; Go to step 15.
14. Perform the aerated fuel test. Refer to section "Aerated Fuel Test – Two-Filter Fuel System". Was fuel aerated?
a. Yes; repair cause of aerated fuel. Refer to section "Aerated Fuel Test – Two-Filter Fuel System".
b. No; replace the Quantity Control Valve (QCV) and Go to step 18. Refer to section "Removal of the Quantity
Control Valve - Two-Filter System".
15. Using DiagnosticLink 8.03 or higher navigate to Service Routines and Fuel System Integrity Check test and select
Manual FSIC. Road test the truck. Does the code set?
a. Yes; Go to step 16.
b. No; replace fuel filters and release unit to customer.
16. Remove the MCM 120-pin connector. Inspect for damage including fuel, water corrosion or bent terminals. Is damage
found?
a. Yes; repair as needed.

6

All information subject to change without notice.

Copyright © 2016 DETROIT DIESEL CORPORATION

02 27-16

02 27-16
b. No; Go to step 17.
17. Install a test MCM using the extension harness and test drive the truck. Does the code come active?
a. Yes; install original MCM and replace Quantity Control Valve (QCV) then Go to step 18. Refer to section
"Removal of the Quantity Control Valve - Two-Filter System".
b. No; replace MCM and verify repair.
18. Using DiagnosticLink 8.03 or higher, check the value of Pressure Limiting Valve (PLV) openings. With key ON,
engine OFF, select the Actions tab in the top tool bar. Select Fuel System, then Pressure Limiting Valve (PLV) Change
or view (RPG_CTR_PLV_OPEN) under "Extended Data Record #5" list. View and record the PLV open counts. Is the
counter greater than 50?
a. Yes; replace the PLV and release unit to customer. Refer to section "Pressure Limiting Valve Flow Test – TwoFilter Fuel System".
b. No; release unit to customer.

All information subject to change without notice.

02 27-16

Copyright © 2016 DETROIT DIESEL CORPORATION

7