Low or dirty transmission fluid (OBD-Codes.com). Mechanical failure inside the transmission (both sources). Blockage inside the transmission main control, or a failed valve body (OBD-Codes.com describes a blockage; RepairPal lists valve body failure). Faulty shift solenoid (OBD-Codes.com). Faulty transmission control module (both sources), or a faulty PCM (RepairPal). Wiring issue (RepairPal). The sources differ on emphasis: OBD-Codes.com puts fluid, solenoids and blocked passages first, while RepairPal's list adds the PCM and wiring and doesn't mention fluid level.

Correct the fluid level, or change dirty fluid and filter if the manufacturer recommends it. Repair wiring or connector faults, or replace a faulty shift solenoid. Repair or replace the valve body (main control) if a passage is blocked. Repair or rebuild the transmission if testing confirms internal mechanical failure. Repair, reprogram or replace the TCM or PCM only after other causes are ruled out.

P0735🔧 Transmission / Gear ratioStop and fix promptly

P0735: Gear 5 Incorrect Ratio (Meaning, Causes, Fixes)

Q: What does P0735 mean?

P0735 means the computer saw that the transmission's 5th gear isn't producing the ratio it expects, or that the transmission isn't going into 5th. Common causes include low or dirty transmission fluid, a faulty shift solenoid, a blocked passage in the valve body (main control), internal transmission wear, wiring problems, or a faulty transmission or powertrain control module. An automatic transmission uses several gear ratios so the engine can stay in its useful range as speed rises, and newer transmissions may have five or more. The transmission control module (TCM), or on some cars the PCM or ECM, uses solenoids to direct fluid pressure that applies the clutches and bands for each gear. OBD-Codes.com says the computer typically compares engine speed with the transmission speed sensor to work out the actual gear ratio and torque converter slip, and sets P0735 when that calculation doesn't match what it expects for 5th gear. RepairPal describes it more simply: it says the TCM sets P0735 when it detects that the transmission is not going into fifth gear. It is a generic OBD-II code for 1996 and newer vehicles, though repair steps vary by make and model. OBD-Codes.com lists similar incorrect ratio codes P0730 through P0734 and P0736, and says any other transmission codes should be fixed first.

Q: Can I keep driving with P0735?

Stop and fix promptly. Have it checked soon and drive gently until you do. RepairPal rates P0735 Urgent, meaning it can cause severe damage or be unsafe. OBD-Codes.com gives no severity rating but lists delayed or missing shifts into 5th gear and a slipping transmission, which can get worse with continued driving. If the transmission slips, flares in RPM or won't shift, stop hard driving and have it diagnosed promptly.

Reviewed 2026-10-23 · Based on 2 cited source(s)

What P0735 means

An automatic transmission uses several gear ratios so the engine can stay in its useful range as speed rises, and newer transmissions may have five or more. The transmission control module (TCM), or on some cars the PCM or ECM, uses solenoids to direct fluid pressure that applies the clutches and bands for each gear. OBD-Codes.com says the computer typically compares engine speed with the transmission speed sensor to work out the actual gear ratio and torque converter slip, and sets P0735 when that calculation doesn't match what it expects for 5th gear. RepairPal describes it more simply: it says the TCM sets P0735 when it detects that the transmission is not going into fifth gear. It is a generic OBD-II code for 1996 and newer vehicles, though repair steps vary by make and model. OBD-Codes.com lists similar incorrect ratio codes P0730 through P0734 and P0736, and says any other transmission codes should be fixed first.

Severity: can I keep driving?

Stop and fix promptly

Have it checked soon and drive gently until you do. RepairPal rates P0735 Urgent, meaning it can cause severe damage or be unsafe. OBD-Codes.com gives no severity rating but lists delayed or missing shifts into 5th gear and a slipping transmission, which can get worse with continued driving. If the transmission slips, flares in RPM or won't shift, stop hard driving and have it diagnosed promptly.

Common symptoms

Check engine light on (OBD-Codes.com)
Delayed shift, or not shifting into 5th gear (OBD-Codes.com; RepairPal says the transmission may not shift properly)
Transmission slipping (OBD-Codes.com)
Worse fuel economy (both sources)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Low or dirty transmission fluid (OBD-Codes.com)
Mechanical failure inside the transmission (both sources)
Blockage inside the transmission main control, or a failed valve body (OBD-Codes.com describes a blockage; RepairPal lists valve body failure)
Faulty shift solenoid (OBD-Codes.com)
Faulty transmission control module (both sources), or a faulty PCM (RepairPal)
Wiring issue (RepairPal)
The sources differ on emphasis: OBD-Codes.com puts fluid, solenoids and blocked passages first, while RepairPal's list adds the PCM and wiring and doesn't mention fluid level

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Check the transmission fluid level and condition first, following your owner's manual procedure. OBD-Codes.com says low or dirty fluid can cause shifting problems in several gears.
Read all stored codes. If there are other transmission codes, such as a shift solenoid circuit code, OBD-Codes.com says to fix those first.
If P0735 is the only incorrect ratio code, OBD-Codes.com suggests a careful test drive to see whether 5th gear actually engages.
Look over the transmission wiring and connectors for damage or corrosion, and check for technical service bulletins (TSBs) for your vehicle.

Typical fixes

Correct the fluid level, or change dirty fluid and filter if the manufacturer recommends it
Repair wiring or connector faults, or replace a faulty shift solenoid
Repair or replace the valve body (main control) if a passage is blocked
Repair or rebuild the transmission if testing confirms internal mechanical failure
Repair, reprogram or replace the TCM or PCM only after other causes are ruled out

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The transmission slips, flares in RPM or won't shift into 5th gear
Diagnosis needs an advanced scan tool to see which gear the TCM commands and whether engine speed matches the calculated transmission output speed (OBD-Codes.com)
Several incorrect ratio codes are stored, which OBD-Codes.com says can point to an internal mechanical problem, a pressure problem or a blocked passage in the main control
OBD-Codes.com says advanced knowledge of transmission operation and overhaul is often needed, along with the factory service manual

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0735 serious?

RepairPal rates it Urgent. OBD-Codes.com gives no rating but lists slipping and missing or delayed shifts into 5th gear. Slipping can wear the transmission faster, so get it diagnosed soon.

Does P0735 mean my transmission is shot?

Not necessarily. Both sources list internal failure as one cause, but OBD-Codes.com says to check fluid level and condition first, and the list also includes shift solenoids, a blocked valve body passage, wiring and the control module.

My car only has four gears. Why would it set P0735?

Neither source covers that case. P0735 refers to 5th gear, and OBD-Codes.com notes that newer transmissions may have more than four ratios. If your transmission doesn't have a 5th gear, have the code confirmed with a good scan tool and check for TSBs.

How much does it cost to fix P0735?

Neither source gives a repair cost. It ranges widely, from a fluid service or wiring repair to a solenoid, valve body or transmission rebuild, so get a diagnosis and a written estimate first.

Sources

Last reviewed 2026-10-23. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.