P0718 — Input/Turbine Speed Sensor A Circuit Intermittent

OBD2 code P0718 flags a problem with the sensor and actuator circuits (input/turbine speed sensor a circuit intermittent). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0718 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the input/turbine speed sensor a for damage, corrosion, chafing or poor contact.
Subsystem check Reproduce the fault: wiggle the harness and tap the input/turbine speed sensor a while watching the live signal; heat and vibration usually make intermittent faults appear.
Subsystem check Measure reference voltage, ground and signal continuity at the component connector.
Subsystem check Wiggle-test the harness while watching the signal in live data — dropouts reveal broken wires.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0718 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0718 (parts and labor, USD, independent shop rates): Repair wiring or connectors: $80–$250; Control module repair: $300–$1,000; Replace the faulty sensor or actuator: $150–$500. Overall, fixing P0718 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What does OBD2 code P0718 mean?

Is it safe to drive with P0718?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

Will P0718 clear itself?

Sometimes P0718 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of P0718?

The most common causes are: blown fuse feeding the circuit, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.

How much does it cost to fix P0718?

Repair wiring or connectors — $80–$250; Control module repair — $300–$1,000; Replace the faulty sensor or actuator — $150–$500. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

When your check engine light comes on and a scan tool reveals P0718, you're looking at a fault with the input or turbine speed sensor circuit — specifically, an intermittent electrical problem. The "A" designation points to one specific sensor in the transmission, and "intermittent" tells you the issue isn't constant: the sensor works correctly some of the time and fails at others. The powertrain control module logs P0718 after confirming the irregular signal across multiple drive cycles, not just on a single bad reading.

The input/turbine speed sensor monitors the rotational speed of gears inside your transmission. This data feeds the control module, which uses it to manage shift timing, line pressure, and torque converter clutch engagement. When the sensor signal drops out or becomes erratic, the module can't make accurate decisions about gear changes. To set P0718, the PCM compares the incoming sensor data against its expected range — if the readings jump around or disappear momentarily, the code triggers. It also captures a freeze frame snapshot recording engine RPM, load, temperature, and vehicle speed at the exact moment the fault occurred.

Intermittent codes like P0718 are notoriously tricky because everything checks out fine by the time you get under the hood. The wire might be broken inside the insulation, holding together through friction until the engine moves or heat expands the harness. A connector pin that's slightly backed out can make solid contact when everything settles, then lose it during acceleration or a sharp turn.

Common symptoms of P0718

Check Engine Light illuminates on the dashboard
The affected transmission system operates intermittently or stops functioning entirely
Possible limp-mode activation with reduced driveability
Increased fuel consumption due to improper shift scheduling
Inconsistent or harsh shifting in automatic transmissions
Temporary loss of certain transmission functions until the fault clears

What causes P0718

The most common culprits behind P0718 are wiring and connection issues, not failed components:

Connector pins that have backed out or lost tension, causing intermittent contact
Wiring broken beneath intact insulation — the outside looks fine but the conductor is fractured
Corrosion or moisture intrusion at the sensor connector
Chafed wiring from contact with heat shields, brackets, or body panels
Poor ground connection affecting the sensor circuit
Blown fuse protecting the affected sensor or control circuit
Internal fault within the sensor or related actuator (less common)
Control module driver failure (rare — always rule out wiring first)
Open or shorted circuits elsewhere in the sensor harness

How to diagnose P0718

Approach P0718 systematically to avoid replacing good parts:

Connect an OBD2 scanner, verify P0718 is stored, and record the freeze frame data — this shows the exact conditions (RPM, load, temperature, speed) when the fault happened.
Check for any related diagnostic trouble codes. Secondary codes often point to the root cause rather than the symptom.
Search for technical service bulletins (TSB) specific to your vehicle make, model, and model year — manufacturers frequently publish known issues and software updates for P0xxx codes.
Perform a thorough visual inspection of the wiring harness and connectors at the input/turbine speed sensor. Look for damaged insulation, greenish corrosion deposits, bent pins, or loose retainer clips.
While monitoring live sensor data on your scan tool, wiggle the harness and gently tap the sensor housing. An intermittent dropout in the data stream confirms a mechanical fault.
Use a multimeter to verify reference voltage, ground integrity, and signal circuit continuity at the sensor connector.
Clear the code, then drive the vehicle through conditions matching the freeze frame data. If P0718 returns, you've confirmed the fault is active and repeatable.

Repair options and costs

Address the cheapest possibilities before considering component replacement:

Wiring repair or connector replacement: $80–$250
Control module diagnosis and repair: $300–$1,000
Input/turbine speed sensor or actuator replacement: $150–$500

Expect to pay $80 to $1,000 total depending on what the diagnosis uncovers. In the majority of P0718 cases, the problem turns out to be a damaged connector or chafed wire — far less expensive than a new sensor or control module. Spending time on proper diagnosis upfront keeps your repair bill predictable.

Can you drive with P0718?

Most vehicles remain drivable after P0718 sets, though you may notice delayed shifts, reduced performance, or a disabled overdrive or tow-haul function. If the transmission slips severely, the engine stalls, or you see brake or steering warnings alongside the code, stop driving immediately and have the vehicle towed. Otherwise, schedule diagnosis within the week — intermittent faults tend to worsen over time.