HINT:

1. For more information on the differential pressure sensor and TOYOTA D-CAT*1, refer to the following procedures.
2. If P1425, P1427 and/or P1428 is present, refer to the DTC chart for TOYOTA D-CAT.

*1: Diesel Clean Advanced Technology.

 

The two sensing chambers of the differential pressure sensor are mounted to monitor the pressure before and after the DPNR*2 catalytic converter. The sensor itself is not located on the engine assembly in order to reduce the influence of vibration. The sensor is a semiconductor-type that is not influenced by exhaust gases.
The ECM compares the exhaust gas pressure before and after DPNR catalytic converter by monitoring the pressure using the upstream and downstream sensing chambers of the differential pressure sensor. If the difference between the pressure before and after the catalytic converter exceeds a predetermined level, the ECM judges that the catalytic converter is clogged with particulate matter (PM). When the ECM judges that a partially clogged condition exists, the ECM begins to perform DPNR catalyst regeneration.
When the output voltage of the sensor deviates from the normal operating range, the ECM interprets this as a malfunction of the sensor circuit, and sets DTC P1425, P1427, or P1428 and illuminates the MIL.
*2: Diesel Particulate-NOx Reduction system

 

HINT:

If the vacuum hoses of the differential pressure sensor are incorrectly connected (crossed), the ECM interprets this as abnormal pressure difference, DTC P1426 (Differential Pressure Sensor [Installation]) will be set and the MIL will illuminate.

Toyota fault code list DTC P1425 DTC P1427 DTC P1428

DTC No.	DTC Detection Condition	Trouble Area
P1425	Differential pressure sensor output voltage is less than 0.4 V, or more than 4.8 V for 3 seconds or more (1 trip detection logic)	Open or short in differential pressure sensor circuit Incorrect differential pressure sensor hose routing Differential pressure sensor ECM
P1427	Differential pressure sensor output voltage is less than 0.4 V for 3 seconds or more (1 trip detection logic)
P1428	Differential pressure sensor output voltage is more than 4.8 V for 3 seconds or more (1 trip detection logic)

HINT:

1. DTC P1426 (Differential pressure sensor [installation]) will be present if there is incorrect vacuum hose routing to the differential pressure sensor.
2. After confirming DTC P1425, P1427 and P1428, check the differential pressure in the "Powertrain / Engine and ECT / Data List / DPNR Differential Pressure" menu using the intelligent tester.

 

Reference: 

Condition	Differential Pressure Output	Sensor Condition
Ignition switch on (IG)	Approximately 0 kPa	Normal
Always	3 kPa	Open or short circuit
3,000 rpm (No engine load)	Negative output	Incorrect arrangement of hose piping

In order to detect abnormality in the differential pressure sensor at any time, the ECM always monitors output voltage from the sensor. When the sensor output voltage deviates from the normal operating range (between 0.4 V and 4.8 V) for more than 3 seconds, the ECM interprets this as a malfunction in the sensor circuit and illuminates the MIL.

1.READ VALUE OF DIFFERENTIAL PRESSURE

1. Connect the intelligent tester to the DLC3.

2. Turn the ignition switch on (IG) and turn the tester ON.

3. Enter the following menus: Powertrain / Engine and ECT / Data List / DPNR Differential Pressure.

4. Check that differential pressure is within the specification below.
    

    

   Result:
    

   Condition	Differential Pressure	Proceed to
   Always	-5 kPa or less	A
   Ignition switch on (IG)	-4 kPa to 98 kPa	B
   Always	99 kPa	C

 

B	CHECK FOR INTERMITTENT PROBLEMS
C	Go to step 3

A

2.CHECK CONNECTION OF VACUUM HOSE (DIFFERENTIAL PRESSURE SENSOR - VACUUM TRANSMITTING PIPE)

1. Check if the vacuum hose routing between the differential pressure sensor and the vacuum transmitting pipe is correct.

2. Check that there is no exhaust gas leakage between the differential pressure sensor and the vacuum transmitting pipe.

 

NG	CORRECT TO NORMAL CONNECTION

OK

3.CHECK BLOCKAGE OF VACUUM HOSE AND TRANSMITTING PIPE

 

CAUTION:

Be careful of being burned by exhaust gases during the following inspection.

 

1. Disconnect the vacuum hose (both upstream and downstream) on the differential pressure sensor.

2. Start the engine.

3. Check if there are exhaust gas pulsations from both vacuum hoses during idling.

 

NG	REPLACE CLOGGED PARTS

OK

4.CHECK WIRE HARNESS (DIFFERENTIAL PRESSURE SENSOR - ECM)

1. Disconnect the B61 differential pressure sensor connector.

2. Disconnect the B32 ECM connector.

3. Measure the resistance of the wire harness side connectors.

    

   Standard resistance:

   Tester Connection	Specified Condition
   B61-2 (PEX) - B32-120 (PEX)	Below 1 ?
   B61-3 (VC) - B32-74 (VCPX)	Below 1 ?
   B61-1 (E2) - B32-97 (EPEX)	Below 1 ?
   B61-2 (PEX) or B32-120 (PEX) - Body ground	10 k? or higher
   B61-3 (VC) or B32-74 (VCPX) - Body ground	10 k? or higher

4. Reconnect the differential pressure sensor connector.

5. Reconnect the ECM connector.

 

NG	REPAIR OR REPLACE HARNESS AND CONNECTOR

OK
REPLACE DIFFERENTIAL PRESSURE SENSOR ASSEMBLY