SFI SYSTEM, Diagnostic DTC:P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135

DTC Code	DTC Name
P0120	Throttle / Pedal Position Sensor / Switch "A" Circuit Malfunction
P0121	Throttle / Pedal Position Sensor / Switch "A" Circuit Range / Performance Problem
P0122	Throttle / Pedal Position Sensor / Switch "A" Circuit Low Input
P0123	Throttle / Pedal Position Sensor / Switch "A" Circuit High Input
P0220	Throttle / Pedal Position Sensor / Switch "B" Circuit
P0222	Throttle / Pedal Position Sensor / Switch "B" Circuit Low Input
P0223	Throttle / Pedal Position Sensor / Switch "B" Circuit High Input
P2135	Throttle / Pedal Position Sensor / Switch "A" / "B" Voltage Correlation

DESCRIPTION

Tech Tips

These DTCs relate to the throttle position sensor.

The throttle position sensor is mounted on the throttle body, and detects the opening angle of the throttle valve. This sensor is a non-contact type sensor. It uses hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds.

The throttle position sensor has 2 sensor circuits, each of which 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 in proportion to the throttle valve opening angle, and are transmitted to the VTA1 terminals of the ECM.

As the valve closes, the sensor output voltage decreases and as the valve opens, the 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. These signals are also used in calculations such as air fuel ratio correction, power increase correction and fuel-cut control.

DTC No.	DTC Detection Condition	Trouble Area
P0120	The output voltage of VTA1 quickly fluctuates beyond lower and upper malfunction thresholds for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) ECM
P0121	The difference between the VTA1 and VTA2 voltages is below 0.8 V or higher than 1.6 V for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Throttle position sensor circuit ECM
P0122	The output voltage of VTA1 is 0.2 V or less for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Short in VTA1 circuit Open in VC circuit ECM
P0123	The output voltage of VTA1 is 4.54 V or higher for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Open in VTA1 circuit Open in E2 circuit Short between VC and VTA1 circuits ECM
P0220	The output voltage of VTA2 quickly fluctuates beyond the lower and upper malfunction thresholds for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) ECM
P0222	The output voltage of VTA2 is 1.75 V or less for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Short in VTA2 circuit Open in VC circuit ECM
P0223	The output voltage of VTA2 is 4.8 V or higher, and VTA1 is between 0.2 V and 2.02 V, for 2 seconds (1 trip detection logic)	Throttle position sensor (built into throttle body) Open in VTA2 circuit Open in E2 circuit Short between VC and VTA2 circuits ECM
P2135	Either of the following conditions is met (1 trip detection logic): (a) The difference between the output voltages of VTA1 and VTA2 is 0.02 V or less for 0.5 seconds (b) The output voltage of VTA1 is 0.2 V or less, and VTA2 is 1.75 V or less, for 0.4 seconds	Short between VTA1 and VTA2 circuits Throttle position sensor (built into throttle body) ECM

Tech Tips

When any of these DTCs are output, check the throttle valve opening angle using the intelligent tester. Enter the following menus: Powertrain / Engine / Data List / All Data / Throttle Position No. 1 and Throttle Position No. 2.

Throttle Position No. 1 is the VTA1 signal, and Throttle Position No. 2 is the VTA2 signal.

Reference (Normal Condition)

Tester Display	Accelerator Pedal Fully Released	Accelerator Pedal Fully Depressed
Throttle Position No. 1	0.5 to 1.1 V	3.2 to 4.8 V
Throttle Position No. 2	2.1 to 3.1 V	4.6 to 5.0 V

MONITOR DESCRIPTION

The ECM uses the throttle position sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm that the throttle position sensor is operating properly.

P0120, P0122, P0123, P0220, P0222, P0223 and P2135

A specific voltage difference is expected between the sensor terminals, VTA1 and VTA2, for each throttle valve opening angle. If the difference between VTA1 and VTA2 is incorrect, the ECM interprets this as a malfunction in the sensor and stores a DTC.
VTA1 and VTA2 each have a specific voltage range. If VTA1 or VTA2 is outside the normal operating range, the ECM interprets this as a malfunction in the sensor and stores a DTC.
VTA1 and VTA2 should never be close to the same voltage level. If VTA1 is within 0.02 V of VTA2, the ECM determines that there is a short circuit in the sensor and stores a DTC.

If the malfunction is not repaired successfully, a DTC is stored 10 seconds after the engine is next started.

P0121

This sensor transmits two signals: VTA1 and VTA2. VTA1 is used to detect the throttle opening angle and VTA2 is used to detect malfunctions in VTA1. The ECM performs several checks to confirm that the throttle position sensor and VTA1 are operating properly.

For each throttle opening angle, a specific voltage difference is expected between the outputs of VTA1 and VTA2. If the output voltage difference between the two signals deviates from the normal operating range, the ECM interprets this as a malfunction of the throttle position sensor. The ECM illuminates the MIL and stores the DTC.

If the malfunction is not repaired successfully, the DTC is stored 2 seconds after the engine is next started.

FAIL-SAFE

When any of these DTCs, as well as other DTCs relating to electronic throttle control system malfunctions are set, the ECM enters fail-safe mode. During fail-safe mode, the ECM cuts the current to the throttle actuator, and the throttle valve is returned to a 7° throttle angle by the return spring. The ECM then adjusts the engine output by controlling the fuel injection (intermittent fuel-cut) and ignition timing, in accordance with the accelerator pedal opening angle, to allow the vehicle to continue at a minimal speed. If the accelerator pedal is depressed firmly and gently, the vehicle can be driven slowly.

Fail-safe mode continues until a pass condition is detected, and the engine switch is then turned off.

WIRING DIAGRAM

INSPECTION PROCEDURE

Tech Tips

These DTCs relate to the throttle position sensor.
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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 INTELLIGENT TESTER (THROTTLE POSITION SENSOR)

Connect the intelligent tester to the DLC3.
Start the engine.
Turn the tester on.
Enter the following menus: Powertrain / Engine / Data List / All Data / Throttle Position No. 1 and Throttle Position No. 2.

Read the values displayed on the tester.

Result
When Accelerator Pedal Released		When Accelerator Pedal Fully Depressed		Trouble Area	Proceed to
Throttle Position No. 1	Throttle Position No. 2	Throttle Position No. 1	Throttle Position No. 2	Trouble Area	Proceed to
0 to 0.2 V	0 to 0.2 V	0 to 0.2 V	0 to 0.2 V	VC circuit open	A
4.5 to 5.0 V	4.5 to 5.0 V	4.5 to 5.0 V	4.5 to 5.0 V	E2 circuit open
0 to 0.2 V, or 4.5 to 5.0 V	2.1 V to 3.1 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	2.1 V to 3.1 V (Fail-safe)	VTA1 circuit open or ground short
0.6 V to 1.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	0.6 V to 1.4 V (Fail-safe)	0 to 0.2 V, or 4.5 to 5.0 V	VTA2 circuit open or ground short
0.5 to 1.1 V	2.1 to 3.1 V	3.2 to 4.8 V (Not fail-safe)	4.6 to 5.0 V (Not fail-safe)	Throttle position sensor circuit normal	B

Tech Tips

DTC P0121 is stored when the voltages output from VTA1 and VTA2 are not consistent with the characteristics of the sensors. Therefore, check the Freeze Frame Data when this DTC is output. Use the following formula to confirm relative differences in voltage.

Characteristic sensor output
VTA2 x 0.8 is approximately equal to VTA1 + 1.11 V
VTA1: Throttle Position No. 1
VTA2: Throttle position No. 2

If DTC P0121 is output, proceed to the "CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)".

CHECK WHETHER DTC OUTPUT RECURS (THROTTLE POSITION SENSOR DTCS) Click here

CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM)

Disconnect the throttle body connector.
Disconnect the ECM connector.

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

Standard resistance (Check for Open)

Tester Connection	Condition	Specified Condition
E17-5 (VC) - E4-34 (VCTA)	Always	Below 1 Ω
E17-6 (VTA) - E4-26 (VTA)	Always	Below 1 Ω
E17-4 (VTA2) - E4-27 (VTA2)	Always	Below 1 Ω
E17-3 (E2) - E4-35 (ETA)	Always	Below 1 Ω

Standard resistance (Check for Short)

Tester Connection	Condition	Specified Condition
E17-5 (VC) or E4-34 (VCTA) - Body ground	Always	10 kΩ or higher
E17-6 (VTA) or E4-26 (VTA) - Body ground	Always	10 kΩ or higher
E17-4 (VTA2) or E4-27 (VTA2) - Body ground	Always	10 kΩ or higher

Reconnect the ECM connector.
Reconnect the throttle body connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (THROTTLE POSITION SENSOR - ECM)

INSPECT ECM (VC VOLTAGE)

Disconnect the throttle body connector.
Turn the engine switch on (IG).

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

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
E17-5 (VC) - E17-3 (E2)	Engine switch on (IG)	4.5 to 5.5 V

Reconnect the throttle body connector.

REPLACE ECM Click here

REPLACE THROTTLE BODY ASSEMBLY
1. Replace the throttle body Click here.
NEXT

CHECK WHETHER DTC OUTPUT RECURS (THROTTLE POSITION SENSOR DTCS)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the tester on.
Clear the DTCs Click here.
Start the engine.
With the vehicle stationary, fully depress and release the accelerator pedal.
Enter the following menus: Powertrain / Engine / DTC.

Read the DTCs.

Result

Result	Proceed to
DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223, and/or P2135 are output	A
DTC is not output	B

END

REPLACE ECM Click here