Wednesday, October 25, 2006

P0121 tps sensor code for 2001 Ford Focus with 2.0L engine.


My sister's 2001 Ford Focus check engine light is on and it is hesitating. After scanning for codes, I got P0121 which is a faulty tps sensor. I am new to this ATS but I have a digital voltmeter, can you send me the procedure in testing this code?

ATS Advisor:

On this tps sensor, you have 3 wires. On one end is the ground wire and the other end is the reference voltage wire. The middle wire is your tps signal voltage. Check out the ground wire and reference voltage wire at the sensor itself. The ground voltage should give you 0.250 volt or less with key on. If reading is higher, you have a shorted wire in your ground wires or the tps sensor. The reference voltage is almost always fixed at 5 volts. Finally, the signal wire is best checked at ecm (computer) terminal pin. With engine at idle, expect to get 0.5 to 1.2 volts. At high idle, the reading goes up to roughly 4.5 to 5.0 volts.
If you are not getting these readings, repair the wires or replace the tps sensor.

ATS Tip:

When you get the ATS wiring diagram, the ecm pin wire color and designation will be shown to you.


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