OBD-II Code · Powertrain
P0793
Intermediate Shaft Speed Sensor "A" No Signal
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$200–$1,200
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
No signal from intermediate shaft sensor.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Limp mode
- No upshift
Likely causes
- Sensor failedMost common
- Wiring open
- Sensor reluctor damaged
Read the full diagnostic procedureP0793 indicates the PCM/TCM is seeing no signal from the Intermediate Shaft Speed Sensor (ISS), the sensor that monitors a mid-transmission shaft (us…
P0793 indicates the PCM/TCM is seeing no signal from the Intermediate Shaft Speed Sensor (ISS), the sensor that monitors a mid-transmission shaft (usually input clutch drum or intermediate planetary) to calculate slip and time shifts. Without ISS data the transmission cannot compute ratio across all gears and typically defaults to a limp or harsh-shift strategy.
Cheapest checks
visually inspect the sensor connector for fluid intrusion and bent pins, then back-probe the sensor while cranking or driving and look for a clean AC waveform on a scope (typical Hall-effect ISS sensors produce a 0 to 5V square wave, while variable-reluctance types produce an AC sine wave that scales with shaft RPM, often 100 mV peak-to-peak at idle climbing to several volts at highway speed). Measure resistance on VR-type sensors against spec (commonly 270 to 360 ohms on GM 6L80, 250 to 400 ohms on Ford 6R80 intermediate sensors); Hall-effect sensors require 5V reference, ground, and signal verification at the connector. Inspect the tone ring on the affected shaft through the pan or speed-sensor port for missing or damaged teeth. Caveat: P0793 can also be triggered by a hardware fault inside the TCM that drops the sensor input, so if the sensor, harness, and tone ring are all confirmed good, the TCM is the next suspect (rare but documented).
Vehicle-specific patterns2006 to 2010 Cadillac Escalade/Chevrolet Tahoe with 6L80 trips P0793 from internal harness ISS wire chafing on the case casting, addressed by GM TSB…
- 2006to 2010 Cadillac Escalade/Chevrolet Tahoe with 6L80 trips P0793 from internal harness ISS wire chafing on the case casting, addressed by GM TSB 10-07-30-005 with revised internal harness.
- 2009to 2014 Ford F-150 with 6R80 sets P0793 from the ISS sensor itself failing internally, a known wear item that Ford addressed with updated part number.
- 2007to 2012 Dodge Caliber/Jeep Compass with CVT (JF011E) sets the equivalent secondary-pulley speed code from CVT step motor or input speed sensor failure.
- 2004to 2009 Nissan Titan with RE5R05A trips P0793 from input/turbine speed sensor failure, Nissan TSB NTB04-073 covers updated sensor.
Estimated repair$180 to $750.
Look up another code
P0793 — frequently asked
What does a P0793 code mean?
No signal from intermediate shaft sensor.
What causes a P0793 code?
Common causes: Sensor failed; Wiring open; Sensor reluctor damaged.
What are the symptoms of a P0793 code?
Typical symptoms: Limp mode; No upshift.
Is it safe to drive with a P0793 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $200-$1,200.
How do I diagnose a P0793 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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