Scania EMS DTC 135 Supply pressure

EMS Engine Management System · Scania · 4 variants

Code 135 (decimal). Some diagnostic tools show it in hexadecimal as 0087.

In short

The fuel pressure in the accumulator is lower than that requested by the control unit when the engine is running.

Variant 1: The fuel pressure in the accumulator is too low

Applies to: EMS10

What does Scania EMS fault code 135 mean?

The fuel pressure in the accumulator is lower than that requested by the control unit when the engine is running.

What causes Scania DTC 135?

- Air in the fuel system. - Clogged fuel filters. - Internal or external leakage in the high pressure side. - Fault in the fuel inlet metering valve. - Insufficient fuel supply from the low pressure side to the high pressure side. - Fault with the high pressure pump.

What are the symptoms?

Black smoke from the engine may appear.

How to fix Scania EMS fault code 135?

  1. Run Safety precautions for the fuel system.
  2. Check that the supply pressure is correct.
  3. Check if there are other fault codes for the fuel feed pump and rectify these first.
  4. Check the condition of the fuel filters and renew them if necessary.
  5. Bleed the fuel system according to WSM > 03-00 Fuel and exhaust systems, assembly.
  6. If fault code 4231 is active, rectify this first.
  7. Check if there are other fault codes related to the injectors and rectify these first.
  8. If fault code 0148 is active, rectify this first.
  9. Troubleshoot the high pressure system by clicking on the links to the wizards.

Variant 2

Applies to: EMS S6

Detection

The feed pressure has been implausibly low in comparison with the nominal pressure for various operating conditions.

Possible cause

The fault can be due to any of the following causes: - One of the overflow valves opens too early. - The fuel shut-off valve is closed. - The fuel filter is blocked. - Air in the fuel or out of fuel. - Defective feed pump. - Serious leakage in the fuel system.

System reaction

For the fault code to be generated, the supply pressure must have been lower than permitted for at least 7 seconds. The time limit has been set so that the fault code will not be generated in the event of a brief pressure deviation which is not caused by a fault. If the voltage is outside the permitted range, the control unit uses a preset value. An active fault code limits the maximum engine torque by approximately 40%. If the fault is only temporary, the fault code may become inactive. The fault code affects the vehicle's emissions of nitrogen oxides (NOx) and the lamp which warns about a high level of contaminants comes on in the instrument cluster. A text message is also displayed in vehicles with NOx monitoring. Vehicles with NOx monitoring An active fault code cannot be cleared from the control unit. When the fault has been rectified, the control unit must verify that the fault has been rectified in order for the fault code to become inactive.

How to fix

  1. For help with troubleshooting the fuel system, see the Workshop Manual > TI 03-07 02 16, Troubleshooting and overhaul of the Scania HPI fuel system.
  2. Make sure there is fuel and bleed the fuel system.
  3. Check whether the fuel shut-off valve is closed.
  4. Check whether the fuel filter is clogged.
  5. Check the feed pump.
  6. Make sure the fuel system is not leaking.
  7. If the fault code is generated while the engine is coasting, i.e. when driving downhill with the accelerator pedal released, you can look at Stored operational data under the Supply pressure tab for help with troubleshooting.
  8. If the supply pressure deviation has been -1.0 bar or more during a certain time period, it is a sign that the fuel filter is starting to get clogged.
  9. If there is only a slight deviation in supply pressure, this may mean that the overflow valve is seizing.
  10. Verification Start the engine and wait for at least 15 seconds.
  11. If the fault is resolved, the fault code becomes inactive.
  12. Clear the fault code.
  13. Switch the power off and on with the starter key 3 times in succession at 10 second intervals to extinguish the warning lamp.

Variant 3: Fuel pressure in accumulator too low

Applies to: EMS S7

Detection

Fuel pressure in the accumulator is below the value requested by the control unit when the engine is running.

Possible cause

- Air in the fuel system. - Blocked fuel filter. - Internal or external leakage in the high pressure side. - Fault in the fuel inlet metering valve. - Insufficient fuel supply from the low pressure side to the high pressure side. - Fault on the high pressure pump.

System reaction

Black smoke from the engine may appear. When this fault code is active, engine power is reduced and the EGR circuit is deactivated, if applicable. The fault code cannot be deleted when it is active.

How to fix

  1. Run Safety precautions for the fuel system.
  2. Check the condition of the fuel filters and renew if necessary.
  3. Bleed the fuel system according to WSM > 03 > 03-00 Fuel and exhaust systems, assembly > Scania XPI fuel system.
  4. If fault code 4231 is active, rectify based on this first.
  5. If there are other fault codes for one of the injectors, rectify based on these first.
  6. If fault code 0148 is active, rectify based on this first.
  7. Run Check for internal leaks.
  8. Run Check of fuel inlet metering valve.
  9. Run Leak testing the safety valve.
  10. Run Plug test – checking for internal leakage using the starter motor.
  11. Run the Cylinder output test.
  12. Run Cylinder balancing.
  13. Troubleshoot the low pressure part, see WSM > 03 > 03-95 Troubleshooting and symptoms > 03:95-05 XPI fuel system, Troubleshooting table.
  14. Troubleshoot the high pressure pump according to instructions, see WSM > 03 > 03-95 Troubleshooting and symptoms > 03:95-05 XPI fuel system, Troubleshooting table.

Variant 4: Fuel pressure in accumulator too low

Applies to: EMS S8

Detection

Fuel pressure in the accumulator is below the value requested by the control unit when the engine is running.

Possible cause

- Air in the fuel system. - Blocked fuel filter. - Internal or external leakage in the high pressure side. - Fault in the fuel inlet metering valve. - Insufficient fuel supply from the low pressure side to the high pressure side. - Fault with the high pressure pump.

System reaction

Black smoke from the engine may appear. When this fault code is active, engine power is reduced and the EGR circuit is deactivated, if applicable. The fault code cannot be deleted when it is active.

How to fix

  1. Run Safety precautions for the fuel system.
  2. Check the condition of the fuel filters and renew if necessary.
  3. Bleed the fuel system according to WSM > 03 > 03-00 Fuel and exhaust systems, assembly > Scania XPI fuel system.
  4. If fault code 4231 is active, rectify based on this first.
  5. If there are other fault codes for one of the injectors, rectify based on these first.
  6. If fault code 0148 is active, rectify based on this first.
  7. Run Check for internal leaks.
  8. Run Check of fuel inlet metering valve.
  9. Run Leak testing the safety valve.
  10. Run Plug test – checking for internal leakage using the starter motor.
  11. Run the Cylinder output test.
  12. Run Cylinder balancing.
  13. Troubleshoot the low pressure part, see WSM > 03 > 03-95 Troubleshooting and symptoms > 03:95-05 XPI fuel system, Troubleshooting table.
  14. Troubleshoot the high pressure pump according to instructions, see WSM > 03 > 03-95 Troubleshooting and symptoms > 03:95-05 XPI fuel system, Troubleshooting table.

This information is for guidance only. Always follow the manufacturer workshop manual and safety procedures; if in doubt, contact an authorised workshop.

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