Low or contaminated transmission fluid (30% likelihood): Degraded or low ATF reduces hydraulic pressure needed for fifth gear engagement, causing slippage and a gear ratio that doesn't match the expected value. Worn fifth gear clutch pack (25% likelihood): The clutch elements responsible for fifth gear may be worn, allowing slippage that the PCM detects as an incorrect gear ratio. Faulty shift solenoid (20% likelihood): The solenoid controlling the 4-5 shift may be electrically faulty or mechanically stuck, preventing fifth gear from properly engaging. Valve body malfunction (15% likelihood): Stuck or worn valve body components can restrict hydraulic flow to the fifth gear circuit. Speed sensor issue (10% likelihood): A failing input or output speed sensor may report inaccurate data, causing the PCM to flag a ratio error.

How much does it cost to fix P0735?

DIY repair typically costs $20–$200 for parts. Professional repair runs $250–$1600 including parts and labor.

P0735

Powertrain

Moderate

Gear 5 Incorrect Ratio

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P0735 means the Powertrain Control Module has detected that the gear ratio in fifth gear does not match the expected value. This code applies to vehicles with 5-speed (or higher) automatic transmissions. The PCM monitors the input and output shaft speed sensors and compares the calculated ratio to the expected fifth gear ratio stored in its programming.

Since fifth gear is typically the highest overdrive ratio, this problem is most apparent during sustained highway driving. You may notice your engine running at higher RPMs than usual at highway speeds, a significant decrease in fuel economy, or the transmission failing to shift into its highest gear. In some cases, the transmission may shift into fifth gear briefly and then drop back to fourth.

Start with a transmission fluid check — low or degraded fluid is the most common and least expensive cause. If the fluid is in good condition, professional diagnosis is recommended. Fifth gear problems on modern multi-speed transmissions often involve solenoid issues or worn clutch components. A qualified transmission shop can run diagnostic tests to pinpoint the exact cause and recommend the most cost-effective repair.

Severity

Moderate — Address SoonThis Week

Symptoms

•Slipping or harsh engagement of fifth gear
•Higher-than-normal RPMs at highway cruising speeds
•Noticeable drop in highway fuel economy
•Check Engine light illuminated
•Transmission may refuse to shift into fifth gear

Likely Causes

Low or contaminated transmission fluid30%

Degraded or low ATF reduces hydraulic pressure needed for fifth gear engagement, causing slippage and a gear ratio that doesn't match the expected value.

Worn fifth gear clutch pack25%

The clutch elements responsible for fifth gear may be worn, allowing slippage that the PCM detects as an incorrect gear ratio.

Faulty shift solenoid20%

The solenoid controlling the 4-5 shift may be electrically faulty or mechanically stuck, preventing fifth gear from properly engaging.

Valve body malfunction15%

Stuck or worn valve body components can restrict hydraulic flow to the fifth gear circuit.

Speed sensor issue10%

A failing input or output speed sensor may report inaccurate data, causing the PCM to flag a ratio error.