Must see! Common post-processing faults of 14 kinds of truck sensors

October 09,2021

1️⃣ Damaged intake pressure and temperature sensor

 

Cause analysis: The intake pressure signal is abnormal, and the ECU cannot receive the correct intake information, which results in abnormal fuel injection. The combustion is insufficient, the engine is sluggish, and black smoke is emitted during the refueling process. Problems with the wiring harness connection and sensor failure can cause this failure.

 

Solution: Check the intake air pressure and temperature sensor.

 

2️⃣ Damage of water temperature sensor

 

Cause analysis: when the water temperature sensor fails and the ECU detects that the output signal of the water temperature sensor is not credible, the substitute value is used. The ECU limits the torque of the engine for the purpose of protecting the engine.

 

Solution: check the water temperature sensor.

 

3️⃣ Damage of oil pressure sensor

 

Cause analysis: the probe of the oil pressure sensor is seriously damaged, the ECU detects that the oil pressure sensor is not connected, and the displayed value of the instrument is the internal substitute value of the ECU.

 

Solution: check the oil pressure sensor.

 

4️⃣ Poor contact of OBD socket terminal

 

Cause analysis: the OBD socket terminal exits, resulting in poor contact, and the diagnostic instrument and ECU cannot communicate.

 

Solution: check the OBD socket terminal.

 

5️⃣ Nitrogen and oxygen sensor wire harness short circuit

 

Cause analysis: the nitrogen and oxygen sensor harness is worn, short circuited and grounded, and the nitrogen and oxygen sensor cannot work normally, resulting in excessive emission, engine torque limit and system alarm.

 

Solution: check the wire harness of nitrogen and oxygen sensor.

 

6️⃣ Post treatment heating relay box damage

 

Cause analysis: Harness open circuit fault.

 

Solution: check and repair the harness of heating relay box.

 

7️⃣ The bottom software of the instrument is wrong and does not send vehicle speed signal

 

Cause analysis: during driving, the vehicle speed signal sent by the instrument suddenly drops to 0. The change of vehicle speed signal leads to the change of ECU control oil volume, resulting in instantaneous fuel cut-off.

 

Solution: update the instrument to the latest version

 

8️⃣ Blockage of urea return pipe of SCR system

 

Cause analysis: the sundries in the urea return pipe are blocked, resulting in the failure of the system to inject urea normally, the emission exceeds the standard, the engine torque limit, and the system alarm.

 

Solution: check the urea return pipe.

 

9️⃣ Phenomenon of terminal socket of connector of urea reflux heating pipeline

 

Cause analysis: connector failure of urea heating return pipe.

 

Solution: repair the terminal and reconnect the plug-in.

 

🔟 Open circuit fault of urea pressure pipeline

 

Cause analysis: the heating wire of the pressure pipe of urea pump is open circuit, which leads to the failure of heating urea normally in winter and the system alarm.

 

Solution: check the pressure pipe of urea pump.

 

1️⃣1️⃣ Open circuit fault of urea suction pipeline

 

Cause analysis: the heating wire of the suction pipe of the urea pump is open circuit, resulting in the failure to heat urea normally in winter and the system alarm.

 

Solution: check the suction pipe of urea pump.

 

1️⃣2️⃣ Open circuit fault of urea return pipeline

 

Cause analysis: the heating wire of the return pipe of urea pump is open circuit, resulting in the failure to heat urea normally in winter and the system alarm.

 

Solution: check the return pipe of urea pump.

 

1️⃣3️⃣ Urea leakage at the electrical connector of urea pump

 

Cause analysis: urea leaks from the electrical connector of urea pump and corrodes the metal pin, resulting in short circuit and open circuit faults.

 

Solution: check the electrical connector of urea pump and replace the damaged one.

 

1️⃣4️⃣ Exhaust temperature sensor harness open circuit

 

Cause analysis: the exhaust temperature sensor harness is damaged, and ECU cannot obtain the exhaust temperature upstream of SCR catalyst, resulting in no pressure build-up and no urea consumption of urea pump, resulting in excessive emission, engine torque limit and system alarm.

 

Solution: repair

 

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