Gear 4 Incorrect Ratio
The transmission is not shifting into or holding gear 4 properly.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The computer is expecting a specific ratio when the vehicle is in 4th gear, but it's not seeing it. This usually means something is wrong with the transmission components or sensors.
What the computer is actually seeing
The Transmission Control Module (TCM) monitors the output speed and input speed sensors. When these values are measured during a shift into 4th gear, they don't match the expected ratio, indicating a problem in the gear engagement.
What a healthy reading looks like
The expected gear ratio in 4th gear typically should be around 1.00:1 to 1.20:1 depending on the gearbox specs. Input speed may be around 2000 RPM while output speed should be close at around 2000 RPM when in gear.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check the transmission fluid level; it should be at the correct level and clean (red and not burnt). Decision: If low or dirty, fill/change fluid and retest; if okay, move to next step.
- 2Inspect wiring and connectors for the input and output speed sensors; look for damage or corrosion. Decision: If damaged, repair or replace; if no issues found, move to the next step.
- 3Test the input and output speed sensors using a multimeter. Input speed should be between 0-5 volts at idle, increasing with acceleration. Compare readings to manufacturer specs. Decision: If out of spec, replace sensor; if readings are correct, proceed to next step.
- 4Perform a transmission fluid pressure test to check for stuck valves or excessive wear. Expected pressure in forward gears is typically 70-100 PSI depending on the transmission. Decision: If pressure is below spec, look for internal issues; if pressures are okay, consider TCM software update.
Common causes
- Low transmission fluid level
- Faulty input or output speed sensors
- Worn or damaged transmission components
- Malfunctioning valve body
- Software issue in TCM
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It's not advisable to drive as you may experience slip or harsh shifts that can cause damage to the transmission.
Will this code come back after resets?
Yes, if the underlying issue is not fixed, the code will likely return.
Why does this code show with P0732 or P0733?
These codes indicate incorrect ratios for other gears, suggesting a systemic issue with the transmission, not just isolated to 4th gear.
Working a real vehicle right now?
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