Transmission Input Sensor Circuit Low
Transmission input sensor voltage is lower than expected.
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What it means (plain English)
The computer is expecting a certain voltage level from the transmission input sensor to know the transmission’s position, but it's getting a lower voltage than it should. This could mean the sensor is faulty, the wiring is damaged, or there's a bad connection.
What the computer is actually seeing
The transmission input sensor typically operates around 0.5 to 4.5 volts depending on the position. When the voltage drops below a threshold (often below 0.5 volts), the fault code is triggered.
What a healthy reading looks like
Look for sensor voltage between 0.5V and 4.5V while in operation.
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.
- 11. Check the wiring and connectors to the transmission input sensor for any visible damage or corrosion. Repair as needed and recheck if the code persists.
- 22. Measure the voltage at the transmission input sensor connector while the vehicle is operating. It should read between 0.5V and 4.5V.
- 33. If the voltage is low, inspect the wiring harness for shorts to ground or open circuits. Repair any issues found and retest.
- 44. If wiring is good and voltage is within range, replace the transmission input sensor and clear the codes.
- 55. If code returns, suspect the TCM or other related faults.
Common causes
- Faulty transmission input sensor
- Wiring issue or damaged connector
- Low transmission fluid level
- Faulty transmission control module (TCM)
- Corrosion at connectors
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable but you may experience transmission issues like hard shifting or unpredictable behavior.
Will the code come back after clearing it?
If the root cause isn't fixed, yes, it will likely return.
Why does this code sometimes pair with SPN 1741?
SPN 1741 could indicate a related issue with the output sensor, which often fails alongside the input sensor.
Working a real vehicle right now?
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