Nissan Frontier D22. Manual - part 264

DTC P0121 TP SENSOR

EC-159

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EC

DTC P0121 TP SENSOR

PFP:16119

Component Description

UBS00D30

NOTE:
If DTC P0121 is displayed with DTC P0510, first perform trouble diagnosis for DTC P0510, 

EC-407

 .

The throttle position sensor responds to the accelerator pedal movement. This sensor is a type of potentiome-
ter which transforms the throttle position into output voltage, and emits the voltage signal to the ECM. In addi-
tion, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal to the
ECM.
Idle position of the throttle valve is determined by the ECM receiving the signal from the throttle position sen-
sor. This sensor controls engine operation such as fuel cut. On the other hand, the “Wide open and closed
throttle position switch”, which is built into the throttle position sensor unit, is not used for engine control.

CONSULT-II Reference Value in Data Monitor Mode

UBS00D31

Specification data are reference values.

SEF105S

MONITOR ITEM

CONDITION

SPECIFICATION

THRTL POS SEN

●

Ignition switch: ON
(Engine stopped)

●

Engine: After warming up

Throttle valve: Fully closed

0.2 - 0.8V

Throttle valve: Fully opened

3.5 - 4.5V

ABSOL TH·P/S

●

Ignition switch: ON
(Engine stopped)

●

Engine: After warming up

Throttle valve: Fully closed

0.0%

Throttle valve: Fully opened

Approx. 80%

EC-160

[KA24DE]

DTC P0121 TP SENSOR

On Board Diagnosis Logic

UBS00D32

FAIL-SAFE MODE

When the malfunction is detected, the ECM enters fail-safe mode and the MIL lights up.

DTC Confirmation Procedure

UBS00D33

Perform “PROCEDURE FOR MALFUNCTION A” first. If the DTC cannot be confirmed, perform “PRO-
CEDURE FOR MALFUNCTION B”. 

NOTE:
If “DTC Confirmation Procedure” has been previously conducted, always turn ignition switch OFF and wait at
least 5 seconds before conducting the next test.

PROCEDURE FOR MALFUNCTION A

 With CONSULT-II

1.

Turn ignition switch ON.

2.

Select “DATA MONITOR” mode with CONSULT-II.

3.

Start engine and let it idle for at least 10 seconds.
If idle speed is over 1,100 rpm, maintain the following conditions
for at least 10 seconds to keep engine speed below 1,100 rpm.

4.

If 1st trip DTC is detected, go to 

EC-163, "Diagnostic Procedure"

 .

 With GST

Follow the procedure “With CONSULT-II”.

PROCEDURE FOR MALFUNCTION B

CAUTION:

Always drive vehicle at a safe speed.

 With CONSULT-II

1.

Start engine and warm it up to normal operating temperature.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible Cause

P0121

Throttle position sensor 
circuit range/performance 
problem

A)

A high voltage from the sensor is sent to 
ECM under light load driving condition.

●

Harness or connectors
(The throttle position sensor circuit is 
open or shorted.)

●

Throttle position sensor

●

Fuel injector

●

Camshaft position sensor

●

Mass air flow sensor

B)

A low voltage from the sensor is sent to 
ECM under heavy load driving condition.

●

Harness or connectors
(The throttle position sensor circuit is 
open or shorted.)

●

throttle position sensor

●

Intake air leaks

Detected items

Engine operating condition in fail-safe mode

Throttle position sensor 
circuit

Throttle position will be determined based on the injected fuel amount and the engine speed.
Therefore, acceleration will be poor.

Condition

Driving condition

When engine is idling

Normal

When accelerating

Poor acceleration

Selector lever

Suitable position except “N” (Higher gear 
position such as 3rd or 4th is better to 
keep low engine rpm.)

Accelerator pedal

Released

Vehicle speed

As slow as possible

SEF058Y

DTC P0121 TP SENSOR

EC-161

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EC

2.

Turn ignition switch OFF and wait at least 5 seconds.

3.

Turn ignition switch ON.

4.

Select  “MANU TRIG” in “DATA MONITOR” mode with CON-
SULT-II.

5.

Select “THRTL POS SEN” and “ABSOL TH·P/S” in “DATA MON-
ITOR” mode with CONSULT-II.

6.

Press RECORD on CONSULT-II screen at the same time accel-
erator pedal is depressed.

7.

Print out the recorded graph and check the following:

–

The voltage rise is linear in response to accelerator pedal
depression.

–

The voltage when accelerator pedal is fully depressed is approx-
imately 4V.
If NG, go to 

EC-163, "Diagnostic Procedure"

 .

If OK, go to following step.

8.

Select  “AUTO TRIG” in “DATA MONITOR” mode with CON-
SULT-II.

9.

Maintain the following conditions for at least 10 consecutive sec-
onds.

10. If 1st trip DTC is detected, go to 

EC-163, "Diagnostic Procedure"

 .

 With GST

Follow the procedure “With CONSULT-II”.

ENG SPEED

More than 2,000 rpm

MAS A/F SE-B1

More than 3V

 COOLAN TEMP/S

More than 70

°C (158°F)

Selector lever

Suitable position

Driving location

 Driving vehicle uphill (Increased engine load) 
will help maintain the driving conditions required 
for this test.

SEF177Y

SEF245Y

SEF178Y

EC-162

[KA24DE]

DTC P0121 TP SENSOR

Wiring Diagram

UBS00D34

BBWA0547E