P0727 code definition
If the P0727 code is stored, it’s a sign that the vehicle’s PCM has received a signal regarding the engine speed from the engine speed input sensor.
What the P0727 code means
The signal that triggers P0727 means that the engine speed input sensor is erratic, irrational or incorrect in some other way. Without an input speed signal that can be relied upon, the transmission in your vehicle can’t provide a useful shifting strategy.
Although it may differ a bit between manufacturers, the majority of PCMs are programmed to anticipate engine speeds to gradually increase until a shift point is reached (engine speed is expected not to exceed output speeds up until this point as well).
It’s when the input speed doesn’t increase gradually or the PCM doesn’t receive a signal (or an erratic one) that the P0727 code will be stored. The Check Engine Light may come on too, but that’s not always the case. With some models, it takes more than one failure cycle before the light comes on.
What causes the P0727 code?
More often than not, the problems that trigger the P0727 code are caused by either a defective transmission output speed sensor or a faulty engine input speed sensor. However, there could be other reasons too, like:
- Wiring, connectors and circuits that are corroded, shorted, opened or damaged
- Defective shift solenoids
- Defective valve body
- Contaminated or dirty transmission fluid that limits flow
- Faulty engine drivability sensors (usually the engine temperature sensor)
- Faulty valve body
What are the symptoms of the P0727 code?
If your vehicle stores a P0727, you’ll probably find out because of harsh shifting. Some of you may actually be unable to shift altogether. Another common symptom associated with this code is a loss of fuel economy.
It also isn’t unusual for the speedometer to fluctuate uncontrollably or even completely stop working. When you decide to park, the engine might stall on you. A vehicle that is reporting P0727 will occasionally also make it clear by having the engine misfire, sag or hesitate. If all that isn’t enough, the Check Engine Light should come on.
This code is often associated with one regarding the output speed sensor.
Despite all of the above, in some uncommon circumstances, drivers notice no adverse symptoms whatsoever.
How does a mechanic diagnose the P0727 code?
Your mechanic will begin by using a code reader to take stock of what is ailing your vehicle. They might also use an oscilloscope. With these tools, the mechanic will measure engine input speeds.
They’ll most likely inspect the related wiring as well as other electrical components involved. Aside from checking for areas where they have become frayed, are disconnected or are otherwise damaged, the mechanic is also looking for wiring and connectors that show signs of transmission fluid or engine oil leaking on them.
After that, the scanner will be connected to the diagnostic connector to record freeze frame data which can be used later.
Common mistakes when diagnosing the P0727 code
One common mistake is thinking that this code relates to a vehicle speed malfunction, engine misfire, driveline malfunction or fuel delivery problem.
How serious is the P0727 code?
If your vehicle can’t properly shift, it’s not going to be much good to you. Even if you’re one of the lucky ones who doesn’t have any symptoms, that could be short-lived. You’re better off taking it to a mechanic ASAP.
What repairs can fix the P0727 code?
The following may fix the P0727 code:
- Repairing and replacing any faulty electrical components
- Replacing a faulty engine input speed sensor
- Replacing a faulty transmission output speed sensor
- Replacing a defective shift solenoid
- Replacing a defective engine drivability sensor
- Replacing contaminated transmission fluid
Additional comments for consideration regarding the P0727 code
While it’s true that the problem could also be due to a faulty PCM, this is incredibly rare.
Need help with a P0727 code?
YourMechanic has certified mobile mechanics who will drive to your home or office to assess and repair your vehicle. You can receive a quote and book an appointment online or talk to a service advisor by calling. 1-800-701-6230.