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Hino P2BAE Fault Code: Feedback Controll

25/10/2024

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TECHNICAL DESCRIPTION

− The DEF injection control feeds back DEF dose if a measured NOx purification quantity deviates from an estimated NOx purification rate. − The NOx sensor measures NOx level and also counts NH3 as NOx.

DESCRIPTION OF MALFUNCTION

− Failure of DEF injection control is detected. − Feedback is reset when the target purification quantity during feedback implementation is stuck at the maximum value. If reset is repeated, this DTC is detected.

DTC SET CONDITION

DTC Detection Condition:

The engine is ON

Judgment Criteria:

Dosing feedback is reset 3 times at an interval of 180 sec. or shorter

RESET CONDITION

After having restored to the normal conditions.

INDICATION, WARNING OR SYSTEM CONTROL REGULATION WHEN THE DTC IS SET

− MIL: ON − DEF injection is stopped. − NOx reduction quantity monitoring is aborted.

SYMPTOMS ON THE VEHICLE WHEN THE DTC IS SET

Symptoms on the Vehicle Due to Backup Control (Fail Safe Function):

Exhaust gas purification function is declined.

PRE-INSPECTION WORK

Check if the battery voltage is in the normal range

AFTER-INSPECTION WORK

− Clear all past DTCs. − Check if no DTC is stored after test drive

POSSIBLE CAUSES

− It is likely that a NOx purification quantity has dropped or NH3 slip has occurred. − When the amount of NOx to be purified is small compared with the amount of DEF solution, NH3-slip will occur. In the NOx sensor, NH3 is functionally counted as NOx; when NH3-slip occurs, therefore, the NOx sensor reading will be higher than the actual value. − NOx sensor 1 (SCR upstream) − If the NOx sensor 1 (SCR upstream) reads low or high NOx due to malfunction, the NOx sensor 2 (SCR downstream) reading may be high due to NH3 slip. − NOx sensor 2 (SCR downstream) − It is likely that the NOx sensor 2 (SCR downstream) reads high NOx. − DEF: Low concentration − DEF dose: Excessively low level of DEF dose − SCR catalyst: When purification performance is degraded by deterioration of the catalyst, feedback control will be activated. NOTE: If no trouble causes are found, it can be suspected that the respective DTC was issued because of a temporary fault condition caused by the freezing of the DEF.