P1271, P1272

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DTC Code	DTC Name
P1271	Fuel Regulator Circuit (EDU Drive)
P1272	Fuel Pressure Regulator Circuit

Table 1. Cross Section Diagram of Pressure Discharge Valve
*1	Return to Fuel Tank Sub-assembly (Low Pressure)
*2	Valve
*3	Solenoid
*4	From Common Rail Assembly (High Pressure)

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DESCRIPTION

The ECM controls the internal fuel pressure of the common rail by opening and closing the pressure discharge valve. When sudden deceleration occurs, the internal fuel pressure will temporarily become higher than usual and combustion noise may result. Therefore the ECM will open the valve temporarily to discharge the excess pressure inside the common rail. Also, the pressure discharge valve opens when the ignition switch is turned off to allow prompt discharge of the common rail internal pressure and so that the engine stops smoothly.

Tip:

For more information on the pressure discharge valve and common rail system, refer to System Description (Click here).
For more information on the injector driver, refer to System Description (Click here).
If P1271 and/or P1272 is present, refer to the DTC chart for the fuel system (Click here).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P1271	Fuel Regulator Circuit (EDU Drive)	Either condition is met (1 trip detection logic): Open or short in pressure discharge valve circuit. There is no valve opening confirmation (INJF) signal from the injector driver to the ECM for a specific number of times consecutively despite the ECM sending valve opening command (PRD) signals after the engine is started.	Open or short in pressure discharge valve circuit Pressure discharge valve Injector driver	Comes on	DTC stored
P1272	Fuel Pressure Regulator Circuit	Pressure discharge valve does not open. Actual pressure decreasing rate deviates from the simulated pressure decreasing rate after the ignition switch is turned off (2 trip detection logic).	Open or short in pressure discharge valve circuit (P1271 is stored simultaneously) Pressure discharge valve Injector driver ECM	Comes on	DTC stored

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P1271

Fuel Regulator Circuit (EDU Drive)

Either condition is met (1 trip detection logic):

Open or short in pressure discharge valve circuit.
There is no valve opening confirmation (INJF) signal from the injector driver to the ECM for a specific number of times consecutively despite the ECM sending valve opening command (PRD) signals after the engine is started.

Open or short in pressure discharge valve circuit
Pressure discharge valve
Injector driver

Comes on

DTC stored

P1272

Fuel Pressure Regulator Circuit

Pressure discharge valve does not open.

Actual pressure decreasing rate deviates from the simulated pressure decreasing rate after the ignition switch is turned off (2 trip detection logic).

Open or short in pressure discharge valve circuit (P1271 is stored simultaneously)
Pressure discharge valve
Injector driver
ECM

Comes on

DTC stored

Table 2. Related Data List
DTC No.	Data List
P1271	Common Rail Pressure Target Common Rail Pressure Pressure discharge valve
P1272

Tip:

After confirming DTC P1271 and/or P1272, check the fuel pressure inside the common rail by entering the following menus:

Powertrain / Engine / Data List / Common Rail Pressure.
P1271:

After clearing the DTC, drive the vehicle at 50 km/h (31 mph) in third gear, and then decelerate by releasing the accelerator pedal. Check that P1271 is not output.
P1272:

After clearing the DTC, start and stop the engine twice (wait 30 seconds or more after turning the ignition switch off before starting the engine the second time), and then confirm that P1272 is not stored.

Table 3. Reference
Engine Speed	Fuel Pressure (kPa)
Idling	Common Rail Pressure is within 5000 kPa of Target Common Rail Pressure
2500 rpm (No engine load)

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CONFIRMATION DRIVING PATTERN

Table 4. P1271
DTC Detection Drive Pattern	Ignition switch ON to off and Drive the vehicle at 50 km/h (31 mph) in third gear, and then decelerate by releasing the accelerator pedal

Table 5. P1272
DTC Detection Drive Pattern	Ignition switch ON to off

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MONITOR DESCRIPTION

P1271 (Open or short in pressure discharge valve circuit):
This DTC will be stored if there is no valve opening confirmation (INJF) signal sent from the injector driver to the ECM despite the ECM commanding the injector driver to open the pressure discharge valve. This DTC refers to an open or short circuit malfunction of the pressure discharge valve circuit, not a malfunction in which a valve is stuck open or closed.
The injector driver monitors the current supplied to the pressure discharge valve to verify that the current flows into the valve. If the current exceeds the specified level, the injector driver interprets this as the INJF signal being low. If this DTC is stored, the ECM enters fail-safe mode and limits engine power. The ECM continues operating in fail-safe mode until the ignition switch is turned off.

P1272 (Pressure discharge valve stuck closed):
The pressure discharge valve will open and discharge the internal fuel pressure from the common rail to the fuel tank when the ignition switch is turned off. In this event, the ECM compares the actual drop rate of the internal fuel pressure and the target drop rate. If the ECM judges that the actual drop rate is smaller than the target, the ECM then determines that the valve is stuck closed and stores this DTC. This DTC will be stored if the internal fuel pressure does not drop to the target after the ignition switch has been turned off.

If this DTC is stored, the ECM enters fail-safe mode and limits engine power. The ECM continues operating in fail-safe mode until the ignition switch is turned off.

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MONITOR STRATEGY

Table 6. P1271
Required sensors	Injector driver
Frequency of operation	Continuous
Duration	3 seconds
MIL operation	1 driving cycle

Table 7. P1272
Required sensors	Fuel pressure sensor
Frequency of operation	Once per driving cycle
Duration	1 second
MIL operation	2 driving cycles

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TYPICAL ENABLING CONDITIONS

Table 8. P1271
Specification
The vehicle is driven at 50 km/h (31 mph) in 3rd gear, and then decelerated by complete release of the accelerator pedal 3 times.

Table 9. P1272
Item	Specification
Item	Minimum	Maximum
Fuel pressure	27000 kPa (275 kgf/cm², 3915 psi)	-
Fuel temperature	0°C (32°F)	-
Battery voltage	11 V	-
The monitor will not run if the fuel pressure sensor, pressure discharge valve circuit or fuel temperature sensor is malfunctioning.

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TYPICAL MALFUNCTION THRESHOLDS

Table 10. P1271
Specification
There are no confirmation signals from the injector driver for a specific number of times consecutively, despite the ECM sending command signals regularly during deceleration.

Table 11. P1272
Specification
The internal pressure stays beyond the specified level after the ignition switch is turned off.

Table 12. *a Pressure Discharge Valve *b Injector Driver *c (Shielded)

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WIRING DIAGRAM

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CAUTION / NOTICE / HINT

Note:

After replacing the ECM, the new ECM needs registration (See page ) and initialization (Click here).

Tip:

After completing repairs, confirm that P1271 and/or P1272 does not recur.
If P0200 and P1271 are present simultaneously, there is an open in the INJF wire harness between the injector driver and ECM, or there is an open in the wire harness for both an injector assembly and the pressure discharge valve.
Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.

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PROCEDURE

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CHECK IF DTC OUTPUT RECURS

Connect the GTS to the DLC3.
Clear the DTCs.
1. Powertrain > Engine > Clear DTCs
Turn the ignition switch off for 30 seconds or more.
Turn the ignition switch to ON.
Drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal. Perform this 3 times.
Enter the following menus: Powertrain / Engine / Trouble Codes.
1. Powertrain > Engine > Trouble Codes

Read the pending DTCs.

Result

Result	Proceed to
P1272	A
P1271	B
P1271 and P1272	B
Other DTCs output	C

AClick here
BClick here
C
GO TO DTC CHARTClick here

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CHECK COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE OPERATION)

Connect the GTS to the DLC3.
Turn the ignition switch to ON and turn the GTS on.

Enter the following menus: Powertrain / Engine / Utility / Pressure Discharge Valve Check.

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Powertrain > Engine > Utility

Tester Display
Pressure Discharge Valve Check

Select "Close to Open Check".

Read the value of "Open and Engine OFF".

OK
0.5 MPa or less

Tip:

When the system is normal, the value of "Open and Engine OFF" should be at or close to 0 MPa.
When the fuel pressure value of "Open and Engine OFF" does not become equal to or less than 0.5 MPa, the pressure discharge valve may be stuck closed.
When the fuel pressure values of "Close and Engine OFF" and "Open and Engine OFF" are both 0 MPa, the pressure discharge valve may be stuck open or there may be a fuel leak.
Perform "Always Closed Check" if the value is not 0 MPa when the pressure discharge valve is open during "Close to Open Check". If the results are the same as during "Close to Open Check", there is a pressure discharge valve operation malfunction.

Result

Proceed to
OK
NG

OKClick here
GO TO STEP 14
NGClick here
GO TO STEP 12

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INSPECT COMMON RAIL ASSEMBLY (PRESSURE DISCHARGE VALVE RESISTANCE)

Inspect the common rail assembly.

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Result

Proceed to
OK
NG

OKClick here
NGClick here

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CHECK HARNESS AND CONNECTOR (PRESSURE DISCHARGE VALVE - INJECTOR DRIVER)

Disconnect the injector driver connector.
Disconnect the pressure discharge valve connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
C121-2 - C82-4 (RLF+)	Always	Below 1 Ω
C121-1 - C81-1 (RLF-)	Always	Below 1 Ω
C121-2 or C82-4 (RLF+) - Body ground	Always	10 kΩ or higher
C121-1 or C81-1 (RLF-) - Body ground	Always	10 kΩ or higher

Reconnect the injector driver connector.

Reconnect the pressure discharge valve connector.

Result

Proceed to
OK
NG

OKClick here
NGClick here
GO TO STEP 9

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CHECK HARNESS AND CONNECTOR (ECM - INJECTOR DRIVER)

Disconnect the injector driver connector.
Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
C83-2 (PRD) - C55-32 (PRD)	Always	Below 1 Ω
C83-5 (INJF) - C55-25 (INJF)	Always	Below 1 Ω
C83-2 (PRD) or C55-32 (PRD) - Body ground	Always	10 kΩ or higher
C83-5 (INJF) or C55-25 (INJF) - Body ground	Always	10 kΩ or higher

Reconnect the injector driver connector.

Reconnect the ECM connector.

Result

Proceed to
OK
NG

OKClick here
NGClick here

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INSPECT INJECTOR DRIVER (POWER SOURCE CIRCUIT)

*a
Front view of wire harness connector

(to Injector Driver)

Disconnect the injector driver connectors.

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
C82-2 (+B) - C82-3 (GND)	Ignition switch ON	11 to 14 V

Reconnect the injector driver connector.

Result

Proceed to
OK
NG

OKClick here
NGClick here

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REPLACE INJECTOR DRIVER

Replace the injector driver.

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Result

Proceed to
NEXT

NEXTClick here

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CHECK IF DTC OUTPUT RECURS (DTC P1271 AND/OR P1272)

Connect the GTS to the DLC3.
Clear the DTCs.
1. Powertrain > Engine > Clear DTCs
Turn the ignition switch off for 30 seconds or more.
Turn the ignition switch to ON.
Drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal. Perform this 3 times.
Enter the following menus: Powertrain / Engine / Trouble Codes.
1. Powertrain > Engine > Trouble Codes

Read the pending DTCs.

Tip:

If no pending DTCs are output, proceed to the next step to check "All Readiness".
Perform the following procedure using the GTS to determine whether or not the DTC judgment has been carried out.

Enter the following menus: Powertrain / Engine / Utility / All Readiness.

Powertrain > Engine > Utility

Tester Display
All Readiness

Input DTC P1271 and P1272.

Check the DTC judgment result.

Result

Tester Display	Result	Proceed to
Pending DTC	P1271 and/or P1272 is output	B
All Readiness	NORMAL	A
All Readiness	ABNORMAL	B

Tip:

If STATUS is INCOMPLETE or N/A, perform the following procedure 3 times: drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal.

A
END
BClick here

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REPAIR OR REPLACE HARNESS OR CONNECTOR

Repair or replace the harness or connector.

Result

Proceed to
NEXT

NEXTClick here
GO TO STEP 14

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GO TO INJECTOR CIRCUIT

Go to injector circuit.

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Result

Proceed to
NEXT

NEXTClick here
GO TO STEP 14

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REPLACE ECM

Replace the ECM.

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Result

Proceed to
NEXT

NEXTClick here
GO TO STEP 14

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REPLACE COMMON RAIL ASSEMBLY

Replace the common rail assembly.

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Result

Proceed to
NEXT

NEXTClick here

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BLEED AIR FROM FUEL SYSTEM

Bleed the air from the fuel system.

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Result

Proceed to
NEXT

NEXTClick here

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CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Connect the GTS to the DLC3.
Clear the DTCs.
1. Powertrain > Engine > Clear DTCs
Turn the ignition switch off for 30 seconds or more.
Turn the ignition switch to ON.
Drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal. Perform this 3 times.
Enter the following menus: Powertrain / Engine / Trouble Codes.
1. Powertrain > Engine > Trouble Codes

Confirm that the pending DTC is not output again.

Tip:

Perform the following procedure using the GTS to determine whether or not the DTC judgment has been carried out.

Enter the following menus: Powertrain / Engine / Utility / All Readiness.

Powertrain > Engine > Utility

Tester Display
All Readiness

Input DTC P1271 and P1272.
Check the DTC judgment result.

Tip:
If STATUS is INCOMPLETE or N/A, perform the following procedure 3 times: drive the vehicle at 50 km/h (31 mph) in 3rd gear, and then decelerate by completely releasing the accelerator pedal.

Result

Proceed to
NEXT

NEXT
END

ECD SYSTEM, Diagnostic DTC:P1271, P1272