P0730 - Incorrect Gear Ratio
P0730 is a generic powertrain diagnostic trouble code indicating Incorrect Gear Ratio. It relates to the Transmission system.
DTC Breakdown (SAE J2012)
| System | Powertrain (P) |
| Type | Generic |
| Subsystem | Transmission |
| Fault Index | 30 |
| Standard | SAE J2012 / ISO 15031-6 |
What does diagnostic code P0730 mean?
The engine control module logged P0730 after detecting a transmission incorrect gear ratio fault, indicating a slip or control module request.
Severity Level & Driveability Details
Severity: High
Transmission faults can cause vehicle driveability loss or lock the transmission in limp mode, making driving unsafe.
Common Symptoms of P0730
- Transmission slipping or shifting harshly.
- Transmission entering 'limp mode' (locked in 3rd gear).
- Check engine light illuminated.
- Erratic shifting or failure to shift into overdrive.
Typical Causes for P0730
- Failed transmission solenoids or valve body.
- Low or dirty transmission fluid.
- Internal transmission component failure (slipping clutch packs).
- Failed Transmission Control Module (TCM).
Diagnostic and Troubleshooting Steps
Check transmission fluid level and condition (smell for burnt odor). Use a scanner to read codes from the TCM. Monitor input/output speed sensor ratios.
Typical Repairs and Fixes
- Topping off or replacing transmission fluid and filter.
- Replacing transmission solenoids or shift valves.
- Rebuilding or replacing the transmission assembly.
- Replacing or reprogramming the TCM.
Sensor Location & Parts Involved
The transmission solenoids and sensor are located inside the transmission pan on the valve body.
Clearing Code & Recurrence
Reset codes to verify the transmission operates correctly.
Emissions & Smog Inspection Impact
High RPMs in limp mode increase exhaust emissions and reduce fuel mileage.
Free Check Engine Code Cheat Sheet (PDF)
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Sources & References
This diagnostic guide is compiled and verified against the following authority sources:
- NHTSA TSB safety reports
- SAE J2012 standard definitions
Frequently Asked Questions about P0730
What does the transmission incorrect gear ratio code P0730 mean?
The engine control module logged P0730 after detecting a transmission incorrect gear ratio fault, indicating a slip or control module request.
Is it safe to drive with the transmission incorrect gear ratio code P0730 active?
No, transmission slipping can leave you stranded.
How much does it cost to repair a transmission incorrect gear ratio code P0730 fault?
Fluid change is $150-$250. Solenoid fixes are $300-$800. Transmission rebuild or replacement is $2,000-$4,000.
What are the common causes of the transmission incorrect gear ratio code P0730?
Trigger conditions for the transmission incorrect gear ratio code P0730 include: Failed transmission solenoids or valve body., Low or dirty transmission fluid., Internal transmission component failure (slipping clutch packs)..
Can I clear the check engine light for transmission incorrect gear ratio code P0730?
Reset codes to verify the transmission operates correctly.
Will the transmission incorrect gear ratio code P0730 cause an inspection failure?
High RPMs in limp mode increase exhaust emissions and reduce fuel mileage.