Abnormal smoke development

When fault tracing, select the symptom that best matches the fault on the vehicle. Fault tracing should be carried out as described in the information for each symptom. This makes fault tracing more efficient by systematically eliminating or documenting faults which may be the symptom cause.

General information

Note: Before fault tracing is started, chock the wheels and release the parking brake.

Note: During fault tracing, the engine should be run at the operating temperature as well as at the temperature where the symptom occurs.

• The colour of the exhaust smoke can, in many cases, reveal which engine system the fault may be in.
• Try to first determine if the smoke problem is caused by poor fuel quality or whether the fuel filled does not meet specifications.
• The unit injector is an important component in the combustion process. Due to this, it can often be suspected as the cause of smoky exhaust. Before a unit injector is replaced, the systems and components outside the combustion chamber should be excluded as a direct cause of the fault.

Fault tracing

Temporary faults can be difficult to trace as the fault may not occur when the vehicle is checked. Fault tracing should be carried out based on the driver's understanding of the fault(s). The information that the driver has provided together the factual data collected should form the basis for how the problem is to be resolved.
Whenever possible, try to recreate the problem in an environment and situation similar to that described by the driver. Begin by determining if anything has recently happened to the vehicle that could affect the electrical system, but which is not related to the engine control system.

Black smoke

There should be no black smoke from a fault free and well maintained engine. Black smoke indicates poor combustion and is caused by excess fuel or shortage of air.
Black smoke that is caused by a fault in a unit injector and where the fault gives abnormally high levels of fuel starvation, can be considered to be a surplus of fuel supplied (incomplete combustion).
A harsh throttle in the exhaust pressure governor prevents the engine's exhaust exchange. In this case the cause of black smoke is a lack of air.

Step 1: Fault code readings

Active and inactive fault codes registered can point to faults, but can also be useful in searching for the symptom cause. Freeze frames with information for specific fault codes, can also be useful when searching for symptom causes.
Fault tracing, using relevant service information, must always be carried out for relevant fault codes. Components/functions of special interest:

• MID 128, Engine control unit

PID 107	Pressure drop, air filter
PPID 122	Engine compression brake, VCB
PPID 123	Exhaust pressure governor, EPG 2 (D12C)
PPID 124	Exhaust pressure governor, EPG 1
SID 1-6	Unit injectors

Step 2: Visual check

• Check engine oil level.
• Check that the air filter is not blocked or damaged.
• Check that the crank house ventilation is not damaged or blocked.
• Check that the installed components, for example the turbocharger, engine ECU, unit injectors, exhaust pressure governor, have the correct part numbers.

Step 3: Tests

The results of the following tests, carried out using VCADS Pro, can show which systems or which components may be the cause of the symptom. These tests can also eliminate components or systems with no faults or malfunctions.

• Cylinder balancing, test
• Shutting off injectors, manually
• Cylinder compression, test
• Inlet and exhaust system, test
• Start and temperature control, function check
  Note. Check that the temperature control function operates correctly. Abnormal smoke generation can occur if the temperature control function is activated incorrectly.
• Auxiliary brake, test (D9A, D12D, D16C)
  Note. Check that the exhaust brake functions correctly. Abnormal smoke generation can occur if the exhaust brake is activated incorrectly.
• Exhaust brake, test (D12C)
  Note. Check that the exhaust brake functions correctly. Abnormal smoke generation can occur if the exhaust brake is activated incorrectly.
• Sensor value check, engine running
• Sensor value check, stationary engine
  Note. Abnormal smoke generation can occur if any or several sensors display abnormal values.

Step 4: Component and function checks

The following checks should be carried out in the specified order until the fault is found. These checks also can help eliminate components with no faults or malfunctions. The number of tests and the sequence depends on the following: the results from tests and fault codes; the vehicle's condition; the vehicle's service and repair history; other symptoms and information from the driver.

• Fuel quality, check
  Check that the fuel quality is good (not mixed with water or other additives).
• Exhaust pipe, check
  Check that there is no damage, blockages or non-approved changes to the exhaust manifold or exhaust pipe.
  See group 25: Charge air, fault detection (Checklist A)
• Air pressure indicator, check
  Check that the pressure drop indicator functions as it should.
  See group 25: Charge air, fault detection (Checklist A)
• Inlet manifold, check
  Check that the inlet manifold is clean internally and undamaged.
  See group 25: Charge air, fault detection (Checklist A)
• Charge air pipe, check
  Check the charge air pipe for visible cracks and external damage and that it is clean internally.
  See group 25: Charge air, fault detection (Checklist A)
• Charge air cooler, check
  Check that the charge air cooler does not leak and that all hoses and connections are not damaged or blocked.
  See group 25: Charge air, fault detection (Checklist A)
• Engine management system, check
  Check that the engine ECU earth connections and supply cables are fault free and correctly tightened.
  See group 25: Engine control system, check (Checklist M)
• Exhaust pressure governor, throttle
  Check that the exhaust pressure governor throttle is not blocked and that it is not stuck in the closed or half closed position.
  See group 25: Exhaust pressure governor, fault detection (Checklist E)
• Exhaust pressure governor, check
  Check the exhaust pressure governor function, input signals, power supply and air supply.
  See group 25: Exhaust pressure governor, fault detection (Checklist E)
• Control valve VCB, check
  Check the condition of the VCB's control valve.
  See group 25: Exhaust brake fault detection (Checklist O)
• Valves and unit injectors, check
  Check that the valves and unit injectors are correctly adjusted.
  See group 25: Valves and unit injectors, adjustment
• Camshaft settings
  Check that the camshaft is correctly set.
  See group 21: Camshaft and flywheel signals, fault detection (Checklist H)
• Rocker arm shaft, oil pressure, check
  Check that the oil pressure in the rocker arm shaft is within the specification value.
  See group 25: Exhaust brake fault detection (Checklist O)

Blue smoke

Blue smoke often is due to mechanical problems that are related to fuel or engine oil. Electrical problems can also cause blue smoke when, for example, sensors give incorrect values to the engine's control unit. Blue smoke may be unburnt fuel or oil. Blue smoke often has a characteristic smell of fuel or oil.
Blue smoke can be caused by:

• Poor fuel quality.
• Poor combustion due to irregular fuel injection.
• Low compression.
• Some of the temperature sensors (for example ambient air temperature or coolant temperature) give incorrect values, i.e. the sensors indicate higher temperatures than the actual temperature. As long as the sensor values are within the sensors' normal operating range, no error code for an unreasonable sensor value is set.
• The start and temperature control function for the exhaust pressure governor does not function (for cold start).
• Preheating is out of operation (for cold start).

Step 1: Fault code readings

Active and inactive fault codes registered can point to faults, but can also be useful in searching for the symptom cause. Freeze frames with information for specific fault codes, can also be useful when searching for symptom causes.
Fault tracing, using relevant service information, must always be carried out for relevant fault codes. Components/functions of special interest:

• MID 128, Engine control unit

PID 94	Feed pressure
PID 100	Engine oil pressure
PID 110	Coolant temperature:
PID 172	Air temperature, inlet
PID 175	Engine oil temperature
PPID 123	Exhaust pressure governor, EPG 2 (D12C)
PPID 123	Buffer air TC (only D12D500)
PPID 124	Exhaust pressure governor, EPG 1

Step 2: Visual check

• Check engine oil level
• Check that the crank house ventilation is not damaged or blocked.
• Check that there is no damage, blockages or non-approved changes to the exhaust manifold or exhaust pipe.
• Check that the installed components, for example the turbocharger, engine ECU, unit injectors, exhaust pressure governor, have the correct part numbers.

Step 3: Tests

The results of the following tests, carried out using VCADS Pro, can show which systems or which components probably cause the symptom. These tests can also eliminate components or systems with no faults or malfunctions.

• Sensor value check, engine running
• Sensor value check, stationary engine
• Inlet and exhaust system, test
• Cylinder compression, test
• Cylinder balancing, test
• Shutting off injectors, manually

Step 4: Component and function checks

The following checks should be carried out in the specified order until the fault is found. These checks also can help eliminate components with no faults or malfunctions. The number of tests and the sequence depends on the following: the results from tests and fault codes; the vehicle's condition; the vehicle's service and repair history; other symptoms and information from the driver.

• Fuel quality, check
  Check that the fuel quality is good (not mixed with water or other additives).
• Air pressure indicator, check
  Check that the pressure drop indicator functions as it should.
  See group 25: Charge air, fault detection (Checklist A)
• Engine management system, check
  Check that the engine ECU earth connections and supply cables are fault free and correctly tightened.
  See group 25: Engine control system, check (Checklist M)
• Inlet manifold, check
  Check that the inlet manifold is clean internally and undamaged.
  See group 25: Charge air, fault detection (Checklist A)
• Charge air pipe, check
  Check the charge air pipe for visible cracks and external damage and that it is clean internally.
  See group 25: Charge air, fault detection (Checklist A)
• Charge air cooler, check
  Check that the charge air cooler does not leak and that all hoses and connections are not damaged or blocked.
  See group 25: Charge air, fault detection (Checklist A)
• Exhaust pressure governor, throttle
  Check that the exhaust pressure governor throttle is not blocked and that it is not stuck in the closed or half closed position.
  See group 25: Exhaust pressure governor, fault detection (Checklist E)
• Exhaust pressure governor, check
  Check the exhaust pressure governor function, input signals, power supply and air supply.
  See group 25: Exhaust pressure governor, fault detection (Checklist E)
• Control valve VCB, check
  Check the condition of the VCB's control valve.
  See group 25: Exhaust brake fault detection (Checklist O)
• Valves and unit injectors, check
  Check that the valves and unit injectors are correctly adjusted.
  See group 25: Valves and unit injectors, adjusting
• Camshaft settings
  Check that the camshaft is correctly set.
  See group 21: Camshaft and flywheel signals, fault detection (Checklist H)
• Rocker arm shaft, oil pressure, check
  Check that the oil pressure in the rocker arm shaft is within the specification value.
  See group 25: Exhaust brake fault detection (Checklist O)

White or grey smoke

White smoke

White odourless smoke when starting and/or during driving during cold weather is completely normal and does not indicate a fault. The white smoke is a result of completely normal small amounts of water in air that evaporates during combustion and condenses when it comes into contact with the cold air. Note that larger cooling areas in the exhaust and silencer system means greater amounts of white smoke generated in cold starts and at low ambient temperatures.
In extreme cases, coolant can get into the engine via an intake or exhaust port and produce white smoke. In such cases, this is indicated by loss of coolant. If it is not possible to start due to the start and temperature control function and the preheater does not function, this results in an increased generation of white smoke.

Grey smoke

Grey smoke is a mixture of black smoke and steam and often occurs during cold weather. Therefore, where grey smoke is generated, the fault detection procedures for black smoke can be used, see Black smoke.

Step 1: Fault code readings

Active and inactive fault codes which are registered, can point to faults but can also be useful in searching for the symptom cause. Freeze frames with information for specific fault codes, can also be useful when searching for symptom causes.
Fault tracing, using relevant service information, must always be carried out for relevant fault codes. Components/functions of special interest:

• MID 128, Engine control unit

PID 45	Starting heater status relay
PID 107	Pressure drop, air filter
PID 111	Coolant level:
PPID 122	Engine compression brake, VEB
PPID 123	Exhaust pressure governor, EPG 2 (D12C)
PPID 124	Exhaust pressure governor, EPG 1
SID 70	Starting heater 1

Step 2: Visual check

• Check engine oil level
• Check the coolant level

Step 3: Tests

The results of the following tests, carried out using VCADS Pro, can show which systems or which components probably cause the symptom. These tests can also eliminate components or systems with no faults or malfunctions.

• Preheat, check
• Start and temperature control, function check
  Note. Check that the temperature control function operates correctly. Abnormal smoke generation can occur if the temperature control function is activated incorrectly.
• Auxiliary brake, test (D9A, D12D, D16C)
  Note. Check that the exhaust brake functions correctly. Abnormal smoke generation can occur if the exhaust brake is activated incorrectly.
• Exhaust brake, test (D12C)
  Note. Check that the exhaust brake functions correctly. Abnormal smoke generation can occur if the exhaust brake is activated incorrectly.
• Inlet and exhaust system, test
• Cylinder compression, test
• Cylinder balancing, test
• Sensor value check, engine running
  Note. Abnormal smoke generation can occur if any or several sensors display abnormal values.
• Sensor value check, stationary engine
  Note. Abnormal smoke generation can occur if any or several sensors display abnormal values.
• Shutting off injectors, manually

Step 4: Component and function checks

The following checks should be carried out in the specified order until the fault is found. These checks also can help eliminate components with no faults or malfunctions. The number of tests and the sequence depends on the following: the results from tests and fault codes; the vehicle's condition; the vehicle's service and repair history; other symptoms and information from the driver.

• Fuel quality, check
  Check that the fuel quality is good (not mixed with water or other additives).
• Carbon monoxide in the coolant, check
  Check that the coolant is free of carbon monoxide.
  See group 23: Poor compression, fault detection (Checklist G)
• Charge air cooler, check
  Check that the charge air cooler does not leak and that all hoses and connections are not damaged or blocked.
  See group 25: Charge air, fault detection (Checklist A)
• Exhaust pressure governor, throttle
  Check that the exhaust pressure governor throttle is not blocked and that it is not stuck in the closed or half closed position.
  See group 25: Exhaust pressure governor, fault detection (Checklist E)
• Exhaust pressure governor, check
  Check the exhaust pressure governor function, input signals, power supply and air supply.
  See group 25: Exhaust pressure governor, fault detection (Checklist E)
• Control valve VCB, check
  Check the condition of the VCB's control valve.
  See group 25: Exhaust brake, fault detection (Checklist O)
• Rocker arm shaft, oil pressure, check
  Check that the oil pressure in the rocker arm shaft is within the specification value.
  See group 25: Exhaust brake, fault detection (Checklist O