📌 What does code P0793 mean?
Code P0793 indicates that the intermediate shaft A speed sensor (or its circuit) is transmitting no signal to the transmission control module (TCM) or the engine control module (ECM).
This sensor is essential in automatic transmissions for measuring the rotational speed of an internal shaft and assisting with gear shift management.
⚠️ Severity of the problem
Severity: moderate to high
The vehicle may continue to run, but with irregular or degraded transmission behavior. This could mask a more serious issue, so prompt repair is strongly recommended.
🔍 Possible symptoms
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Harsh or irregular gear shifts
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Unstable engine RPM
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Dashboard warning lights illuminated (Check Engine, ABS, traction control, etc.)
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Abnormal driving behavior (unstable idle, jerking)
❗ Common causes
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Faulty speed sensor (dirty, damaged, misaligned)
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Damaged wiring or connectors (short circuit, corrosion, broken wires)
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Problem with the TCM or ECM
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Other related sensors failing (input, output, etc.)
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Transmission fluid (ATF) dirty, burnt, or insufficient
🛠️ Diagnostic steps and solutions
✅ Step 1: Check ATF condition and level
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Low level or dirty fluid → replace according to manufacturer recommendations
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Check for leaks or burnt smells
✅ Step 2: Locate and inspect the sensor
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The sensor is usually on the transmission housing
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Remove obstructing components (air filter, brackets)
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Visually inspect the sensor and its connector: dirt, corrosion, improper connection
✅ Step 3: Clean the sensor
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If accessible, remove the sensor and clean it with brake cleaner
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Check that there are no metal shavings or debris stuck
✅ Step 4: Test the sensor and its circuit
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Use a multimeter to test continuity and resistance according to manufacturer specifications
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Also perform tests at the TCM/ECM connector to check wiring harness integrity
💡 Additional tips
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A misaligned sensor may rub against the reluctor ring → adjust spacing if necessary
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When in doubt, replace the sensor: it’s inexpensive compared to a complete transmission failure
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Record all other active codes (ABS, traction control, etc.) to get an overall view of the problem