P0715
PowertrainInput/Turbine Speed Sensor Circuit Malfunction
This can go either way on cost, so don't panic before you've had it diagnosed. The input speed sensor tells the gearbox how fast the turbine shaft coming out of the torque converter is spinning, and the transmission control module uses that figure to time every gear change. When the signal drops out or reads nonsense, the box can't shift properly, so it drops into limp mode to protect itself. The fix might be a £60 sensor and twenty minutes, or it might mean the box has to come apart, and that's the bit you need to find out first.
ⓘ Information only. This page provides general educational information about fault code P0715. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0715 mean?
P0715 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Input/Turbine Speed Sensor Circuit Malfunction.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Harsh, jerky, or badly delayed gear changes that weren't there before
- • Gearbox locks into one gear and won't change, usually third, the classic limp mode behaviour
- • Engine warning light on, sometimes a transmission warning too
- • Speedometer flickering or jumping around while you drive
- • Car wants to stall or shudders as you slow to a stop
- • Flat acceleration or a hesitation when you put your foot down
Possible causes
Causes commonly associated with P0715, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. The input speed sensor itself has failed, the most common cause by a wide margin. They sit in a hot, vibrating environment and the internal coil eventually gives up
- 2. Wiring or connector fault in the sensor circuit. Look for chafed insulation, green corrosion on the pins, or a connector that's worked loose
- 3. Gearbox oil seeping up the loom and into the connector. ATF wicks along the wires and corrodes everything it touches, very common on older autos
- 4. Metal swarf clinging to the magnetic tip of the sensor, throwing the reading out. Usually a sign the box is shedding material internally
- 5. Worn or chipped reluctor ring on the input shaft, so the sensor has nothing clean to read
- 6. Torque converter trouble affecting turbine speed, less common but worth ruling out
- 7. Transmission control module or software glitch, rare, and only after everything else checks out
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Plug in a scanner and pull every stored code, then watch the turbine speed live while a mate drives or while it's on the road. A signal that drops to zero or spikes randomly points straight at the sensor or its wiring
- 2. Find the sensor and inspect the connector and loom hard. Oil contamination and corroded pins are behind a huge share of these, and you can often spot it by eye
- 3. Pull the sensor and check the magnetic face for swarf or filings. Wipe it clean and look at what came off, that tells you a lot about the box's health
- 4. Measure the sensor's resistance and reference voltage with a multimeter against the manufacturer's figures. A coil that's gone open or short shows up immediately
- 5. Back-probe the connector and check the signal is actually reaching the control module through the loom
- 6. If the sensor and wiring all check out, you're into the reluctor ring, torque converter, or internal gearbox territory, and that's a job for someone who knows that particular box
Common questions about P0715
How do I know if it's the sensor or just dodgy wiring behind it? +
You can't tell from the dashboard, you have to look. The quickest split is to unplug the connector and check it for oil and corrosion, then measure the sensor's resistance against spec. If the sensor reads correctly but the live signal still cuts out when you wiggle the loom, your problem is in the wiring or the connector, not the part. Oil tracking up into the plug is so common on higher-mileage autos that a lot of garages clean and reseal the connector first before spending money on a new sensor. Replace the sensor only after you've proven the wiring is sound, otherwise you fit a good part and the fault comes straight back.
How long is this off the road for? +
If it's a sensor you can get at from outside the box, you're looking at under an hour of labour once the part's in hand. Some sensors are external and easy, others mean dropping a guard or working from above with the airbox out, which pushes it to a couple of hours. Where it stings is if the sensor sits inside the gearbox, because then the pan or even the box has to come off, and that's most of a day plus a fresh fluid fill. Reluctor ring or torque converter work is a one to two day job at most garages.
Is a cheaper aftermarket sensor any good or should I stick with the proper part? +
A decent branded aftermarket sensor from a name like Bosch, Febi, or Meyle is fine and saves you a fair bit over main dealer pricing. Where I'd be careful is the £8 eBay specials, because speed sensors are precision items and a poorly made one will give you intermittent faults that are miserable to chase down. On some newer boxes the control module is fussy about signal quality and won't be happy with a cheap copy. Spend on a recognised brand, skip the bargain-bin stuff, and if it's a known troublesome box just buy genuine and have done with it.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →