P0121 code problem

SOURCE: 97 buick riviera check engine light

The code is for the TPS , several things can cause this tps not plugged in , or plugged in after the car was started. If the car runs good go to auto zone let them erase the code for free with their scanner and then see if it comes back on. most likely it was just a accident. but go check to make sure it is plugged in and that the wires to it are not pinched in any way.

Tom Shanks

• 141 Answers
• Posted on Aug 21, 2009

SOURCE: I have engine light on and I got the check engine

A code P0121 may mean that one or more of the following has happened:

• TPS has intermittent open or short internally
• Harness is rubbing and causing an open or short in the wiring
• Bad connection at the TPS
• Bad PCM (less likely)
• Water or corrosion in connector or sensor

• The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
• There could be a vacuum leak downstream of the MAF sensor.

• In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
• Inspect all vacuum and PCV hoses, replace if necessary
• Check for a dirty fuel filter and proper fuel pressure

SOURCE: My check engine light is on. The code is P0121

where is the throttle position sensor switch located on a 2001 dodge durango?

Jim Chang

• 22 Answers
• Posted on Jan 26, 2011

SOURCE: engine light, vsc, vsc off come on. code P0121 and P0120

It is your Throttle Position Sensor (TPS), the black component on the side of your Throttle Body normally on the right side as you look from the front of your engine.

Take the **** of a screw driver and tap the TPS, while the car is on, you might notice a fluctuation. tapping again may not yield a response but it is prone to jolts.

Before replacing it, try to check the resistance with a Digital Volt Meter on the terminals. You can check Haynes Book at a local supply store that might have it or go to a book store that carry the books. Each series of Lexus/Toyota have there own value. If the values are off, loosen the mounting screws and turn the TPS clock wise until you get the values needed. A slight movement is all that is needed or tolerated so take care not to over adjust or the fix will not work.

If you want to just replace it then not where it is positioned and place the new one starting at a counter clock wise postion then place the new TPS and rotate to exact position the old one was and then tighten down. Caution it is best to check the resistance values to insure proper adjustment.

Hope this helps

SOURCE: Check engine light is on with code # P0121

Diagnostic Test Code (DTC) P0121
The PCM provides the TP sensor with 5 volts on the 5-volt reference circuit and a ground on the low reference circuit. Rotation of the TP sensor rotor from the closed throttle position to the wide open throttle (WOT) position provides the PCM with a signal voltage from less than 1 volt to greater than 4 volts through the TP sensor signal circuit. When the conditions for running this DTC are met, the PCM will use the manifold absolute pressure (MAP) sensor to determine if the predicted operating range of the TP sensor is correct. If the PCM detects the TP sensor voltage is out of the predicted range, DTC P0121 sets.
With that said, I have personally seen a lot of DTCs (especially those that are related to the low-voltage circuits of the throttle control) being caused by "fretting" or corrosion in the wire connectors. This is becoming more common as the manufacturer adds more electronic controls onto the vehicles and have changed the size of the connector pins to "save space". This leaves the connectors with much less surface area with which to make a connection and makes this problem occur much easier.
The first step in any type of electrical diagnosis is a visual and physical inspection of the wiring harness connectors for integrity. Many times, the vehicle may be repaired just by disconnecting and reconnecting the connectors. As with all repairs to wiring harness connectors and terminals, a pull test of the terminals within the connector should be performed. A pull test is performed by inserting the proper size terminal test tool (not a paper clip) into the terminal to determine whether or not the terminal is making good contact, or whether the terminal has been damaged from the prior improper connection or lack of connection.
Note: Most terminals used in current module connectors (ECM, BCM, EBTCM and the like) are small 0.64 mm sq. terminals and can be damaged by probing with the wrong tool.
The J 3561 6-64A or B probe has been designed for these terminals that may be both a round or square design.

Please also note that an error in the Mass Airflow and/or MAP sensor reading can also cause this code because inaccurate inputs from these sensors will cause the computer to under or over estimate the correct throttle position sensor expected reading.