Throttle Position Sensor

P0121 HYUNDAI - Throttle/Pedal Position Sensor/Switch 'A' Circuit Range/Performance

Possible causes - Faulty throttle position sensor - Throttle position sensor harness is open or shorted - Throttle position sensor circuit poor electrical connection - Faulty Engine Control Module (ECM) What does this mean? When is the code detected? Malfunction is detected when an excessively low or high voltage from the sensor is sent to ECM. Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light) P0121 Hyundai Description The throttle position sensor (TPS) responds to the accelerator pedal movement. This sensor is a kind of potentiometer which transforms the throttle position into output voltage, and emits the voltage signal to the Engine Control Module (ECM). In addition, 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 sensor. 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.

Your engine has likely worn out. You are describing the situation when the piston rings are so heavily worn that gas pressure forces itself into the engine sump, pressurizing the lower oil case, and forcing itself into the evaporation system, which then makes its way to the air filter housing.

I advise doing a compression check on the engine at your local garage and repairing or replacing the engine if necessary.

There's a good chance the Throttle Position Sensor (TPS) has gone bad. Have an electrician bench test it for bad spots (in the potentiometer). You may also have carbon/soot buildup on the throttle body thottle plate causing it to stick. Standard throttle/choke plate cleaner will take care of the throttle plate.

Numerous possible causes. First thing I suggest you check/inspect is the Throttle Position Sensor. This sensor is located on the throttle body and has a three-pin connector connected to it. You'll want to find out if the sensor (it's a potentiometer, a rheostat) has any poor contact points inside. This can be done by using an analog ohm meter. If you don't know how to do this, ask someone who does to show you. What you'll be doing is checking to see if the 'resistance' in the potentiometer changes erratically as you rotate the throttle opening, indicating there are bad spots in the pot. If this is the case, the pot is sending these signals to the engine computer, and the computer (ECU) uses this voltage/resistance signal to compute the engine load expected by the driver's input on the accelerator pedal.

Replace the throttle position sensor (TPS) (since you've checked/replaced anything else which could be causing this problem - except WIRING). Reinspect all wiring & connectors/connections before replacing the TPS. Also, I've seen (on occasion, a faulty "Main Relay" create the condition you describe). Suppose you have a faulty ignition switch (ignition key). When placed in the 'START' position, the engine starts normally, BUT, when you release IT to the 'RUN' position, the engine dies - CLUE?

I'm a Platinum Certified Hyundai Technician. Low RPM and Limp Home are always accompanied by each other. Throttle body cleaning FIRST - see what that does. ETS motor not probable, crank position sensor (maybe, because engine stops).. if crank position sensor, there's usually a diagnistic trouble code which identifies it. Clean the throttle body first... then see what happens.

I have an idea... why don't you have a 'qualified Hyundai Technician' diagnose the problem?.. First of all, you describe an Engine Management System problem. I assume it a 1.6 DOHC engine. There are numerous suspect causes for your problem. Example, Idle speed actuator, Cam Position Sensor, Throttle Position Sensor, Injectors, Crank Position Sensor, Manifold Absolute Pressure Sensor, Engine Coolant Temp Sensor, Heated Oxygen Sensors, Mass Airflow Sensor (this one's my favorite.. along with Throttle position sensor), Intake Air Temperature Sensor, and the list goes ON... vacuum leaks, throttle body problems, PCV problems, Oh!.. and let's not forget plugs, wires, coils, fuel pump problems, etc. The one most often found as cause for excessive rev is the ECU (Engine Control Unit). Try this out... disconnect the battery. Take the the pos (+) cable and connect/touch it to the neg (-) cable for 60 seconds.. then reconnect the cables to the battery. Tell me what happens after you drive it for awhile. If it's still acting up... take it in for diagnosis.

Did youmtry disconnecting the battery for five minutes, then reconnect, start engine and let it idle for 5 minutes with everything off, including radio and heater. If this don,t work you may have a faulty position sensor. I hope this helps.

ok when the check engine light comes on that usually indicates a engine malfunction...what you can do is go to your local autozone and they can do an OBDII test for free..my bet says it is the cam or crank sensor.. DO NOT SHUT THE CAR OFF AT AUTOZONE..LOL

The sensor is on the side of the throttle body, it has three wires going to it, it is connected to the throttle blade so when the throttle is opened it reads that info and sends it to the PCM.