P0730 Code: Incorrect Gear Ratio
The transmission computer sees input and output shaft speeds that don't fit the gear it selected.
Stop driving
Drive gently and only as far as a shop: a slipping transmission grinds its own clutch material into debris quickly, and a modest repair can become a rebuild. If the engine revs up and the car doesn't pick up speed, stop and arrange a tow.
At a glance
Severity: High
- Meaning
- Incorrect Gear Ratio
- System
- Transmission · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $100–$6,500
- DIY difficulty
- Hard
The transmission control module knows which gear it has commanded and which ratio that gear must produce. It divides input (turbine) shaft speed by output shaft speed, and when the result stays off the expected value for longer than a calibrated time, it stores P0730. This generic code is used when the error can't be pinned to a single gear, or on vehicles whose makers don't use the gear-specific codes P0731–P0735. Slip caused by low fluid or low line pressure, general clutch wear and a bad input or output speed signal are the usual culprits. CVTs have no fixed gears, so there P0730 means the actual pulley ratio differs from the target ratio; several Nissan/Jatco CVTs use it to report belt slip.
How to read P0730
- P Powertrain
- 0 Generic (SAE)
- 7 Transmission
- 30 Specific fault
Symptoms
- Engine rpm flares during or between shifts without matching acceleration
- Slipping or delayed engagement that gets worse once the fluid is hot
- Transmission stuck in one gear (limp mode), commonly 2nd or 3rd
- Unusually firm shifts as the computer raises line pressure to compensate
- Burnt smell, dark fluid or a fresh leak under the car
- Check engine light, often alongside P0700 or a speed sensor code
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Low fluid level from a leak (cooler lines, pan gasket, axle or pump seal)
- Clutch packs or bands worn across several gears from mileage or overheating
- Low line pressure: pressure control solenoid, clogged filter or worn pump
- Faulty input or output speed sensor signal or wiring
- Stuck shift solenoid leaves the transmission in a gear other than the one commanded
- Internal leakage past worn sealing rings or piston seals
- Lost adaptive values or outdated TCM software after battery or repair work
Diagnosis step by step
Pull every transmission code
Read the TCM with a scan tool that can reach it and record the freeze frame: commanded gear, vehicle speed and fluid temperature. Fix any speed sensor code such as P0715 or P0720 first, because a bad sensor makes a healthy transmission look like it slips.
Tools: OBD-II scanner
Check fluid level the correct way
Many late-model automatics have no dipstick and are checked at a fill plug with the engine running and the fluid at the temperature the procedure calls for, read on the scan tool. A transmission a quart or two low will slip under load and when hot.
Tools: OBD-II scanner, Flashlight, Towels & shallow pan
Calculate the ratio in each gear
On a road test, log input speed, output speed and commanded gear, then divide input by output. A GM 4L60E, for example, should read about 3.06 in 1st, 1.63 in 2nd, 1.00 in 3rd and 0.70 in 4th. Slip in every gear points to fluid, pressure or a shared clutch; slip in only one or two gears points to the clutch or band that works in those gears.
Tools: OBD-II scanner
Sanity-check the speed sensors
In a 1:1 gear with the converter locked, input speed should equal engine rpm, and output speed should track vehicle speed smoothly. Dropouts or spikes to zero on the graph mean a sensor or wiring fault, not slip.
Tools: OBD-II scanner, Multimeter
Have line pressure measured
A transmission shop fits a gauge to the line pressure port and checks idle and stall pressure in Drive and Reverse. Pressure low in every range suggests the pump, filter, regulator valve or pressure control solenoid; normal pressure with slip points to worn friction parts.
Inspect the pan before deciding
Drop the pan and look at the filter and magnet. Light gray paste is normal; bronze flakes, friction material or steel slivers mean internal wear that a fluid service won't cure.
Tools: Towels & shallow pan, Torque wrench, Flashlight
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Fix leak and top up with the specified fluid | No | $100–$350 |
| Fluid and filter service with adaptive relearn | No | $180–$450 |
| Replace input or output speed sensor | No | $150–$450 |
| Replace pressure control solenoid or valve body | No | $450–$1,500 |
| Rebuild or remanufactured transmission | No | $2,800–$6,500 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Nissan
On Nissan Xtronic CVTs (Altima, Rogue, Sentra and others), P0730 is how the TCM reports that the steel belt is slipping on the pulleys. Check CVT fluid level and condition with the correct Nissan CVT fluid; if the belt or pulleys are damaged, the usual repair is a replacement CVT rather than an overhaul.
Field data
| Dodge | 5 | Challenger, Durango, Caliber | |
|---|---|---|---|
| Jeep | 3 | Patriot, Grand Cherokee | |
| Honda | 2 | Pilot |
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
P0730 turns on the check engine light, which fails an OBD-based smog or emissions test. After repairs, clear codes and drive until the readiness monitors are set before retesting.
Frequently asked questions
Is P0730 the transmission or just a sensor?
It can be either. If the ratio jumps around wildly or drops to zero, suspect a speed sensor or its wiring; if the engine truly revs up without the car accelerating, the transmission is slipping.
Will a fluid change fix P0730?
Only if the cause is low or badly degraded fluid and the clutches are still healthy. Fresh fluid can't rebuild worn friction material, so if the pan shows lots of debris, budget for a rebuild.
Why does it only slip when the transmission is hot?
Hot fluid is thinner, so worn seals and a tired pump leak more pressure away. Slip that appears after 20 minutes of driving and disappears after cooling is a classic sign of internal leakage or a low fluid level.
What does P0730 mean on a CVT?
A CVT changes ratio continuously, so there are no individual gears to monitor. P0730 then means the measured pulley ratio doesn't match what the TCM is targeting, which usually indicates belt slip, pressure problems or a faulty speed sensor.