P0718🔧 Transmission / Speed sensingStop and fix promptly

P0718: Input/Turbine Speed Sensor A Intermittent (Meaning, Causes, Fixes)

Reviewed 2026-10-25 · Based on 2 cited source(s)

What P0718 means

The input/turbine speed sensor reads how fast the transmission's input shaft is spinning; OBD-Codes.com notes that 'input' and 'turbine' speed sensor are two names for the same part, depending on the manufacturer. OBD-Codes.com describes it as usually a 3-wire electromagnetic sensor near the rear of the bell housing, reading grooves or a notched reluctor wheel on the input shaft. The powertrain control module (PCM) compares input speed with output speed, engine speed, throttle position and engine load, and stores P0718 when the input speed or circuit voltage doesn't stay accurate for a set time; P0718 specifically indicates an intermittent input circuit voltage. RepairPal describes the input speed signal as telling the transmission control module (TCM) how fast the engine is spinning so it can pick the right gear, and says the PCM or TCM sets P0718 when that signal is inaccurate. The sources differ on the sensor itself: OBD-Codes.com describes a dedicated sensor in the transmission case, while RepairPal says most vehicles use the crankshaft position sensor for this information, so check the service manual for your vehicle. It is a generic OBD-II code, though repair steps vary by make and model. Related codes include P0715 (circuit), P0716 (range/performance) and P0717 (no signal) for the same sensor.

Severity: can I keep driving?

Stop and fix promptly

Get it diagnosed soon and drive gently until you do. RepairPal rates P0718 Urgent, meaning it can cause severe damage or be unsafe. Both sources say the transmission may not shift properly, and OBD-Codes.com adds erratic or harsh shift points and an erratic or dead speedometer. Because the fault comes and goes, the car may drive normally one minute and shift badly the next. If the transmission shifts harshly, won't shift, or the speedometer quits, avoid highway driving and have it checked.

Common symptoms

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

  1. Faulty input/turbine speed sensor (OBD-Codes.com)
  2. Damaged, loose or burnt wiring or connectors (both sources list wiring)
  3. Metal debris built up on the sensor's magnetic tip (OBD-Codes.com)
  4. PCM failure or a PCM programming error (both sources list the PCM)
  5. Transmission control module (TCM) failure (RepairPal)
  6. Crankshaft position sensor failure (RepairPal)
  7. The sources differ on causes: OBD-Codes.com points to the transmission input speed sensor, its wiring, debris and the PCM, while RepairPal lists the crankshaft position sensor, PCM, TCM and wiring and does not name a separate input speed sensor

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

  1. Read all stored codes and write down the freeze frame data. If there are also output speed sensor codes, OBD-Codes.com says to use live scanner data to see which circuit is actually failing.
  2. Check for technical service bulletins (TSBs) for your vehicle; there may be a known fix.
  3. Inspect the input speed sensor's wiring and connector for damage, burnt or loose pins, and look for transmission fluid in the connector; OBD-Codes.com says some sensors leak internally.
  4. Check the battery, battery cables and ends, and alternator output, as OBD-Codes.com recommends.
  5. If you remove the sensor, be careful: OBD-Codes.com warns hot transmission fluid can escape. Clean metal debris off the magnetic tip, check the reluctor wheel or grooves for wear, and make sure the mounting surface is clean, since sensor-to-reluctor clearance is critical.

Typical fixes

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

  • The transmission shifts harshly, slips, or won't shift
  • The fault is intermittent and hard to catch; OBD-Codes.com says an advanced scanner and possibly an oscilloscope may be needed
  • Testing needs the service manual's resistance and voltage specs; OBD-Codes.com warns that testing without disconnecting related controllers can damage them
  • The wiring and sensor check out and the code comes back, which points to a computer or programming problem

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0718 serious?

Treat it as serious. RepairPal rates it Urgent, and both sources say the transmission may not shift properly. Because the signal drops in and out, shifting can change without warning, so drive gently and get it diagnosed soon.

What's the difference between P0717 and P0718?

Both are for the same input/turbine speed sensor A circuit. P0717 means no signal at all, while P0718 means the signal is intermittent or erratic, which often points to loose connections, damaged wiring or debris on the sensor.

Can P0718 affect my speedometer?

It can. OBD-Codes.com lists an erratic or inoperative speedometer and odometer among the symptoms.

How much does it cost to fix P0718?

Neither source gives a repair cost. The price depends on whether it's wiring, the sensor, or a computer problem, so get a diagnosis or a written estimate before replacing parts.

Sources

  1. OBD-Codes.com: P0718 Input/Turbine Speed Sensor A Circuit Intermittent
  2. RepairPal: P0718 Input/Turbine Speed Sensor "A" Circuit Intermittent (rated Urgent)

Last reviewed 2026-10-25. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.