P0120 OBD-II Trouble Code: TPS "A" Circuit Malfunction

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0120 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0120 code

P0120 is a diagnostic trouble code (DTC) for "TPS "A" Circuit Malfunction". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P0120 DIAGNOSTIC Get a fair and transparent estimate upfront

check engine light logo

P0120 code definition

Throttle Pedal Position Sensor/Switch (TPS) "A" Circuit Malfunction

What the P0120 code means

P0120 is the generic OBD-II code which indicates that the Engine Control Module (ECM) has seen the TPS sensor circuit A output voltage going below or above the sensor's expected range, or is chattering when compared to TPS sensor circuit B.

What causes the P0120 code?

  • The ECM detected that the output from TPS sensor circuit A went outside of the specified voltage range in relation to TPS sensor circuit B.

  • The TPS sensor circuit A output falls below .2 volts or goes above 4.5 volts.

What are the symptoms of the P0120 code?

  • The ECM turns on the Check Engine Light and goes into failsafe mode by cutting the current to the throttle actuator to put the throttle valve at approximately less than 6 degrees opening.

  • The ECM controls fuel injection and timing to control engine speeds.

  • The vehicle would be able to be driven very slowly with limited throttle response.

  • The engine may idle higher than normal, but will not accelerate properly.

Note: The symptoms are determined by the manufacturer failsafe ECM strategy for the vehicle during a failure and may vary between manufacturers and vehicles.

How does a mechanic diagnose the P0120 code?

  • Scans and documents the codes received and views the freeze frame data to see when the code was set

  • Resets the codes to clear the OBD-II fault codes and retests the vehicle to see if the code comes back

  • Visually checks all of the TPS connections and wiring for any loose or damaged items.

  • Compares the data between TPS circuit A and B with a scanner, and if incorrect, replaces the TPS as directed by the pinpoint testing.

Common mistakes when diagnosing the P0120 code

  • Not performing a visual inspection first

  • Not scanning, documenting, clearing, and retesting for codes to verify failures

  • Not replacing an TPS sensor when tests indicate a problem

  • Not comparing TPS sensor A and B to be within specification before and after repair or replacements

How serious is the P0120 code?

The P0120 code will put the engine ECM to go into a failsafe mode, which will cause various drive complaints until repairs are done. For example, lack of acceleration, high idle, bucking or jerking, limited speeds, and possible stalling depending on the manufacturer failsafe mode strategy.

What repairs can fix the P0120 code?

Additional comments for consideration regarding the P0120 code

  • The P0120 code may be accompanied by other TPS codes, so following the manufacturer pinpoint tests for each code received may be needed to fix the complaint.

  • Most failures for code P0120 involve a defective TPS sensor not tracking the throttle angle correctly.

  • All TPS related codes will enable the failsafe mode and cause the same drive symptoms.

Need help with a P0120 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
trouble codes
P0120

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0120 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

3,788

Rating Summary
3,460
163
43
24
98
3,460
163
43
24
98

Michael

45 years of experience
75 reviews
Michael
45 years of experience
Great
2002 KIA OPTIMA - CHECK ENGINE LIGHT IS ON - MEMPHIS, TENNESSEE

Joe

17 years of experience
95 reviews
Joe
17 years of experience
Great
2001 OLDSMOBILE AURORA - CHECK ENGINE LIGHT IS ON - CHICAGO, ILLINOIS

William

15 years of experience
90 reviews
William
15 years of experience
He was wonderful even if my car was beyond repair
2006 FORD FREESTAR - CHECK ENGINE LIGHT IS ON - ELMWOOD PARK, ILLINOIS

James

27 years of experience
349 reviews
James
27 years of experience
Awesome mechanic, very professional and knowledgeable, will definitely be using James again.....he’s my new mechanic for ALL my vehicles
1997 DODGE B3500 - CHECK ENGINE LIGHT IS ON - ORLANDO, FLORIDA

More related articles

Symptoms of a Bad or Failing Flexible Clutch Hose
Common signs include difficulty shifting, low clutch fluid, and feeling no resistance at the clutch pedal.
P0121 OBD-II Trouble Code: TPS "A" Circuit Range Performance Problem
P0121 code definition Throttle Pedal Position Sensor/Switch (TPS) A Circuit Range Performance Problem...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...

Related questions

Q: code p0446

Hi there. A P0446 (evaporative emissions system gross leak detected-Toyota defined meaning) sets when there is a fault detected in the evaporative system. The evaporative system is an emissions system responsible for preventing the leakage of fuel vapor into the...

Q: Tranny erratic shift if the problem is in the tcm would it throw a faulty tcm code ?or not all the times this happens.

Hello and thank you for contacting Your Mechanic. The code P0760 means that the shift solenoid "C" is operating irregularity. The code P0870 means that the transmission fluid pressure is not determined at its specified pressure. Check the harness to...

Q: Fault code p0120

Diagnostic trouble code P0120 sets when the ECM (or PCM) receives an output from TPS sensor circuit A that is outside of the specified voltage range in relation to TPS sensor circuit B. The code will also set if TPS...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com