P0721 OBD-II Trouble Code: Output Speed Sensor Range/Performance

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0721 code

P0721 is a diagnostic trouble code (DTC) for "Output Speed Sensor Range/Performance". 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. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 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$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0721 DIAGNOSTIC Get a fair and transparent estimate upfront

P0721 code definition

The P0721 code is a sign that the TCM (transmission control module) isn’t properly converting incoming pulse signals.

What the P0721 code means

On vehicles with electronically-controlled transmissions, the OSS (output shaft speed sensor) is positioned at the end of the output shaft. It’s right before the drive axles so that it can take readings of the shaft’s speed. This is done primarily to determine when to shift, the schedule for torque converter engagement and EPC (electronic pressure control) inside the transmission.

If the PCM/ECM (powertrain control module/engine control module) has determined that the OSS sensor is malfunctioning, the P0721 code will be triggered. However, it may still be able to work by substituting values from other sensors to determine torque converter operation, shift timing, and EPC pressure.

What causes the P0721 code?

Causes of P0721 include:

What are the symptoms of the P0721 code?

The code is generally accompanied by the Check Engine Light. You may also notice that the speedometer isn’t reading correctly. Delayed shifting or trouble shifting at all are also very common symptoms. You may hear a grinding sound or experience resistance when trying to shift. In some cases, the engine will actually stall when you come to a stop. The engine could even misfire.

However, in some rare cases, there actually aren’t any real noticeable symptoms except for the P0721 code itself.

How does a mechanic diagnose the P0721 code?

Most mechanics will begin by removing the OSS to see if it’s the root of the problem. If any of its teeth are missing or have become worn, they’ll need to be replaced, but the code will most likely disappear after the OSS is repaired and reinstalled. They may also test the resistance put forth by the OSS.

The wiring harness should also be inspected for any indication of damage or loose connections. Dirty terminals would be enough to cause the code as well. In vehicles with TFT (transmission fluid temperature) sensors in-line with the OSS sensors, the former should also be checked for resistance.

Common mistakes when diagnosing the P0721 code

One big mistake is diagnosing the P0721 as a problem with engine/turbine speed or as an issue with the internal transmission. Another pretty common misdiagnosis is blaming fuel delivery problems. In any case, the mistake leads to unnecessarily replacing the vehicle speed sensor.

How serious is the P0721 code?

If your speedometer isn’t reading correctly, you’ll want to get the P0721 code addressed right away. Not knowing how fast you’re going could result in an accident or an otherwise avoidable speeding ticket.

Otherwise, the issue is mostly going to be an annoying inconvenience. No one likes stalling out or hearing a jarring noise when their vehicle is shifting (that noise also reflects internal damage – another reason to get this addressed ASAP).

What repairs can fix the P0721 code?

The work necessary to make the P0721 code disappear may include:

  • Removing the OSS sensor and inspecting its condition, especially its teeth and the sensor’s resistance
  • Inspecting the wiring harness for loose connections or wires that have been damaged
  • Checking the power that goes into the OSS sensor as well as the PCM harness

Additional comments for consideration regarding the P0721 code

With some vehicles, the OSS sensor works with the TFT. This means that if there is a problem with the second sensor, the first will suffer as well. The P0721 code could also be caused by poor wiring between the two. If another code is present that has to do with the TFT, that’s a pretty good sign that it’s playing a part in the P0721 code.

Need help with a P0721 code?

If your vehicle is displaying a P0721 code, YourMechanic is here to help. We can send a certified mobile mechanic to your place of work or home – whichever is most convenient. Just sign up on our site or call 1-800-701-6230 to speak with one of our service advisors. They’ll walk you through the process and provide you with a free quote.

trouble codes
P0721
Check Engine Light

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0721 code.

SCHEDULE P0721 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

5,606

Rating Summary
5,180
205
50
34
137
5,180
205
50
34
137

James

40 years of experience
34 reviews
James
40 years of experience
Ford F-150 - Check Engine Light is on - Chagrin Falls, Ohio
Jim was great! Arrived on time, quickly diagnosed the problem and recommended further work. Very helpful, I’ll use Jim again and recommend to family and friends.

Roberto

11 years of experience
137 reviews
Roberto
11 years of experience
Nissan Titan - Check Engine Light is on - Spring, Texas
Roberto was very thorough with his explanation of repairs needed. I will contact your mechanic for future repairs.

Matthew

32 years of experience
839 reviews
Matthew
32 years of experience
Kia Optima - Check Engine Light is on - Yorktown, Virginia
Matthew Lerman was God Sent, and thank God for Your Mechanic,, you have my Vote Looking , Looking forward for more Business. Very Honest Guy

Robert

20 years of experience
38 reviews
Robert
20 years of experience
Honda Accord - Check Engine Light is on - Brentwood, California
He came earlier than on time and got the job done faster than I seen anyone else have . Solid honest hard working dude.


Related questions

I have a 2009 VW Jetta S 2.5L. Why does my car turns on but then it turns off after driving it for a bit/while?

These are the following definitions for the codes you've received: P0864 - Transmission control module (TCM) communication circuit -range/performance problem P0070 - Ambient Air Temperature Sensor - (possibly shorted but most likely not related) P0734 - Gear 4 Incorrect...

Diagnostic code P0721

Hi....the best thing to do is request a diagnostic based on the trouble code, P0721, that you have in hand. Resolve that first as the fault behind the trouble code may account for the shift difficulty you are having. The...

More related articles

P0530 OBD-II Trouble Code: A/C Refrigerant Pressure Sensor Circuit Malfunction
P0530 means there is a malfunction with the A/C refrigerant sensor circuit often due to low refrigerant or excessive system pressure.
P0203 OBD-II Trouble Code: Injector Circuit Malfunction - Cylinder 3
P0203 code definition P0203 is a general OBD2 code that points to a fault in the injector circuit. Note: This...
P0269 OBD-II Trouble Code: Cylinder Number 3 Contribution/Balance Fault
P0269 P0269 code definition Cylinder Number 3 Contribution/Balance Fault What the P0269 code means P0269 is an OBD-II diagnostic trouble code which indicates that the engine control module (ECM) detected the cylinder number 3 having low contribution to the running...

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 (855) 347-2779 · hi@yourmechanic.com