P0715: Input/Turbine Speed Sensor — Diagnosis
Table of contents
Key Takeaway
P0715 relates to the transmission input speed sensor. Here's what it does and how it fails.
P0715 means the input/turbine speed sensor
What P0715 Means
The input/turbine speed sensor monitors how fast the transmission input shaft is spinning. The TCM uses this to calculate shift points and torque converter slip. See our [OBD-II codes pillar](/codes/) for related transmission codes.
Symptoms
| Symptom | Why |
|---|---|
| Harsh or erratic shifting | TCM cannot calculate correct shift points |
| Speedometer malfunction | Speed calculation affected |
| Limp mode (stuck in one gear) | TCM defaults to safe mode |
| Check engine light + P0700 | TCM stored a fault |
| No tachometer reading | Sometimes linked |
Common Causes
| Cause | Fix Cost |
|---|---|
| Failed speed sensor | $100 – $250 |
| Wiring damage/corrosion | $50 – $200 |
| Poor electrical connection | $0 (clean connector) |
| Contaminated transmission fluid | $100 – $200 (fluid change) |
| Internal transmission issue | $1,000+ |
STEER reads transmission codes other scanners miss
A parts-store free scan often comes back "P0700 - check transmission" with no further detail because the scanner cannot access the TCM. The [STEER OBD-II adapter](/obd2-scanner/) reads both ECM and TCM codes, so P0715 (or whichever companion code is present) appears in the same scan view. Pair with the [AI Mechanic](/ai-mechanic/) for plain-English explanations.
Frequently Asked Questions
Can I drive with a P0715 code?
Depends on whether the transmission is in limp mode. If shifts are happening (even if harsh), short-distance driving to a shop is reasonable. If the TCM has dropped to limp mode (stuck in one gear, top speed limited), do not push the car — drive to the nearest safe location and shut down. Continued driving in limp mode rarely causes additional damage but the protective mode exists for a reason.
How much does it cost to fix P0715?
For a sensor-only repair, parts are $50-$150 and labor is 1-2 hours depending on whether the sensor is external (easy) or internal to the transmission case (requires fluid drain). Total $150-$400 at a shop. Wiring repairs are usually cheaper if you can find the damaged wire. Internal transmission issues that cause the sensor to misread are $1,000+ and require a transmission specialist to diagnose.
What's the difference between input and output speed sensor?
Input speed sensor (P0715) measures the speed of the transmission input shaft (after the torque converter, before the gear sets). Output speed sensor (P0720) measures the output shaft speed (going to the driveshaft and wheels). The TCM compares the two to determine actual gear ratio in real time. Either sensor can fail independently with different code numbers.
Why does my car shift hard with a P0715 code?
Without an accurate input speed reading, the TCM cannot precisely calculate the right moment to engage the next gear or how aggressively to apply clutch packs. The TCM falls back to default shift values, which are usually firmer and less smooth than the calibrated values it uses with valid sensor data. Shifts feel rough but the transmission is otherwise operating, just without the sensor-informed refinement.
Get plain-English answers on your iPhone
STEER reads your car's codes the moment they trigger and translates them into something you can act on.
Related reads
Keep going. These pair well with what you just read.
- Diagnostics
P0700: Transmission Control System Malfunction Explained
P0700 sounds scary but it's just an informational code. Here's what it really means.
6 min read - Diagnostics
P0720: Output Speed Sensor — Causes and Fix
P0720 is the output speed sensor. It monitors how fast the transmission output shaft spins.
6 min read - Diagnostics
Car Jerks When Shifting + Check Engine: Causes
Jerking when shifting plus check engine light? Here are the most likely causes.
6 min read - Diagnostics
P0128: Coolant Thermostat — Very Common Code
P0128 is extremely common, especially in cold weather. It's usually the thermostat.
6 min read