SFI SYSTEM, Diagnostic DTC:P0121 and P0221

DTC Code	DTC Name
P0121	Throttle / Pedal Position Sensor / Switch "A" Circuit Range / Performance
P0221	Throttle / Pedal Position Sensor / Switch "B" Circuit Range / Performance Problem

DESCRIPTION

Tip:

This ETCS (Electrical Throttle Control System) does not use a throttle cable.

The throttle position sensor is mounted on the throttle body with motor assembly, and detects the opening angle of the throttle valve.

The throttle body with motor assembly sensor has 2 sensor circuits which each transmits a signal, VTA1 and VTA2. VTA1 is used to detect the throttle valve angle and VTA2 is used to detect malfunctions in VTA1. The sensor signal voltages vary between 0 V and 5 V. The VTA1 sensor signal voltage varies in proportion to the throttle valve opening angle, and is transmitted to the VTA1 terminals of the ECM.

As the valve closes, the VTA1 sensor output voltage decreases, and as the valve opens, the VTA1 sensor output voltage increases. The ECM calculates the throttle valve opening angle according to these signals and controls the throttle actuator in response to driver inputs.


DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P0121	Throttle / Pedal Position Sensor / Switch "A" Circuit Range / Performance	Both of the following conditions are met for 0.4 seconds (1 trip detection logic): The difference between the sensor output of VTA1 and VTA2 is 6.3% or more. The difference between the sensor output of VTA1 and assumed throttle angle with manifold absolute pressure sensor is 9% or more.	Throttle position sensor (throttle body with motor assembly) Throttle position sensor circuit ECM	Comes on	DTC stored
P0221	Throttle / Pedal Position Sensor / Switch "B" Circuit Range / Performance Problem	Both of the following conditions are met for 0.4 seconds (1 trip detection logic): The difference between the sensor output of VTA1 and VTA2 is 6.3% or more. The difference between the sensor output of VTA2 and assumed throttle angle with manifold absolute pressure sensor is 9% or more.	Throttle position sensor (throttle body with motor assembly) Throttle position sensor circuit ECM	Comes on	DTC stored

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

DTC P0121 and P0221 are detected when the vehicle is driven in the city at 30 to 50 km/h (19 to 31 mph) for 5 minutes.

CAUTION / NOTICE / HINT

Note:

After replacing the ECM and/or throttle body with motor assembly, perform electronic throttle learning and idle learning.
Click here
If any DTCs related to the crankshaft position sensor sensor, throttle position sensor and accelerator pedal sensor assembly are output simultaneously, inspect the VC circuit of each component.

Tip:

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, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

READ VALUE USING GTS (THROTTLE POSITION SENSOR)

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

Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Throttle Position No.1 and Throttle Position No.2.

Powertrain > Engine and ECT > Data List


Tester Display
Throttle Position No.1
Throttle Position No.2

Read the values displayed on the GTS.

Result


When Accelerator Pedal Fully Released		When Accelerator Pedal Fully Depressed		Trouble Area	Proceed to
Throttle Position No.1 (VTA1)	Throttle Position No.2 (VTA2)	Throttle Position No.1 (VTA1)	Throttle Position No.2 (VTA2)	Trouble Area	Proceed to
4.8 to 4.98 V	0 to 0.2 V	4.8 to 4.98 V	0 to 0.2 V	VC circuit open	A
4.5 to 4.98 V	0 to 0.2 V	4.8 to 4.98 V	0 to 0.2 V	ETA circuit open
0 to 0.2 V, or 4.8 to 4.98 V	3.9 to 4.4 V	0 to 0.2 V, or 4.8 to 4.98 V	3.9 to 4.3 V	VTA1 circuit open or shorted to ground
0.6 to 1.1 V	0 to 0.2 V, or 4.8 to 4.98 V	0.7 to 1.1 V	0 to 0.2 V, or 4.8 to 4.98 V	VTA2 circuit open or shorted to ground
0.6 to 1.1 V	3.9 to 4.4 V	4.2 to 4.54 V	0.46 to 0.76 V	Throttle position sensor circuit normal	B

B

CHECK WHETHER DTC OUTPUT RECURS (DTC P0121 OR P0221)Click here

A

CHECK HARNESS AND CONNECTOR (THROTTLE BODY WITH MOTOR ASSEMBLY - ECM)

Disconnect the throttle body with motor assembly connector.
Disconnect the ECM connector.

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

Standard Resistance


Tester Connection	Condition	Specified Condition
B15-5 (VC) - B31-115 (VC)	Always	Below 1 Ω
B15-6 (VTA) - B31-84 (VTA1)	Always	Below 1 Ω
B15-4 (VTA2) - B31-83 (VTA2)	Always	Below 1 Ω
B15-3 (E2) - B31-116 (ETA)	Always	Below 1 Ω
B15-5 (VC) or B31-115 (VC) - Body ground	Always	10 kΩ or higher
B15-6 (VTA) or B31-84 (VTA1) - Body ground	Always	10 kΩ or higher
B15-4 (VTA2) or B31-83 (VTA2) - Body ground	Always	10 kΩ or higher
B15-3 (E2) or B31-116 (ETA) - Body ground	Always	10 kΩ or higher

Result


Proceed to
OK
NG

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY

Replace the throttle body with motor assembly.
Click here
Perform electronic throttle learning and idle learning.
Click here

Result


Proceed to
NEXT

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs.

Powertrain > Engine and ECT > Clear DTCs
Turn the ignition switch off and wait for at least 30 seconds.
Start the engine.
Turn the GTS on.
Drive the vehicle at between 30 to 50 km/h (19 to 31 mph) for 5 minutes.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Read the DTCs.

Powertrain > Engine and ECT > Trouble Codes

OK

DTCs are not output.

Result


Proceed to
OK
NG

OK

END

NG

REPLACE ECM

Click here