Hino P2202 Fault Code: Nox Sensor (SCR Upstream) And Heater – Circuit

28/11/2025

Technical Description 

  • NOx sensor 1 (SCR upstream) is controlled by the NOx sensor controller.
  • The NOx sensor controller is connected via the engine ECU and DCU through CAN communication, and it sends and receives data.

Description Of Malfunction

Failure of circuit inside NOx sensor 1 (SCR upstream) is received from CAN data.

DTC Set Condition

DTC Detection Condition:

Starter switch ON.

Judgment Criteria:

Failure of NOx sensor 1 (SCR upstream) internal circuit (Low failure flag) is received from CAN data.

Reset Condition

After having restored to the normal conditions.

Indication, Warning Or System Control Regulation 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

  • Failure of NOx sensor 1 (SCR upstream)
  • Failure of circuit inside sensor
  • Failure of NOx sensor controller

Step 1) Check the DTC detected (DCU) [Diagnostic Tool].

  1. Connect the vehicle to the diagnostic tool.
  2. Set the starter switch to the “ON” position.
  3. Select [DCU] and check if a CAN communication system malfunction U029D has been detected.

Has DTC U029D been detected?

Yes – Go to the diagnostic procedure of a related DTC.  No – Replace the NOx sensor 1 (SCR upstream). Clear all past DTCs.

Check if no DTC is stored after test drive.

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