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Hino P0027 Fault Code: Exhaust Brake Performance

29/11/2024

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Description of malfunction

The engine ECU detected sticking of the exhaust brake valve

DTC set condition

DTC detection condition:

DPR regeneration is in process

The vehicle speed is 0 km/h {0 mph}
The time of 60 seconds has elapsed after the exhaust brake was actuated

Judgment Criteria:

The difference between the fuel injection quantity while the exhaust brake is working and the fuel injection quantity when the exhaust brake is not actuated is 5 mm3/st or less. And also, the difference between the air flow while the exhaust brake is working and the air flow when the exhaust brake is not actuated is -50 mg/cyl or more.

Reset condition

Immediately after normal status is resumed

Indication, warning or system control regulation when the dtc is set

MIL: ON
SVS light: OFF

Symptoms on the vehicle when the dtc is set

Symptoms on the Vehicle Due to Malfunction:

The exhaust brake does not work
DPR regeneration is not terminated successfully

Pre-inspection work

Check that the battery voltage is in the normal range

After-inspection work

Clear all past DTCs
Check that no DTC is detected after test drive

Possible causes

Abnormality in characteristics of air flow sensor
Diesel throttle sticking
Bend, clogging, and crack of piping and hose
Improper adjustment of exhaust brake valve
Malfunction of exhaust brake valve

Inspection procedure

Troubleshooting steps

Step 1: Check the DTC detected 1 [Diagnostic Tool].

Set the starter switch to the “LOCK” position
Connect the vehicle to the diagnostic tool
Set the starter switch to the “ON” position
Select [Engine], and check if any DTC listed below other than P0027 has been detected. (P0101, P04D5, P2101)

Has a DTC other than P0027 been detected?

Yes	Go to the diagnostic procedure of a related DTC.
No	Go to Step 2

Step 2: Inspect the exhaust brake valve piping and hose

Check the piping and hose, connected to the exhaust brake valve, for bend, clogging, and crack.

Were any failures found?

Yes	Connect securely, repair if needed
No	Go to Step 3

Step 3: Inspect the exhaust brake valve

Check the exhaust brake valve for unease and sticking.

Were any failures found?

Yes	Clean the exhaust brake valve. Replace if needed. After clearing or replacement, go to Step 4
No	Go to Step 5

Step 4: Check the DTC detected 2 [Diagnostic Tool]

Perform a DPR forced regeneration
After completion of regeneration, reload the DTC and check if the DTC P0027 has been detected

Has DTC P0027 been detected?

Yes	Go to Step 5
No	Procedure completed

Step 5: Inspect the exhaust brake valve [Diagnostic Tool]

Warm up the engine. (Coolant temperature: 80°C {176°F} or more).
Turn OFF the devices that place load on the engine, such as the air conditioner.

Inspection Procedure:

Select [Engine] on the screen of the diagnostic tool.
Select [Data monitor setting] and [Active test setting].
Select [Target rpm] from [Active test setting] and set the engine revolution to 980 r/min.
Select [Injection quantity] from [Data monitor setting].
Turn ON/OFF the exhaust brake switch and check the difference between the injection quantity of the injector while the exhaust brake is working and the injection quantity when the exhaust brake is not actuated.

MEASUREMENT CONDITIONS

STANDARD VALUES

Engine revolution: 980 r/min Engine coolant temperature: 80°C {176°F} or more.

Turn OFF the air conditioner, and other devices that place load on the engine.

10 – 14 mm3/st

Do the measurements meet the standard value? (There should be a change in the injection quantity between while the exhaust brake is working and when it is not actuated)