P0793Generic code

P0793 Code: Intermediate Shaft Speed Sensor A No Signal

The P0793 code means the computer sees no signal at all from intermediate shaft speed sensor A. The main effect is limp mode. Check that the sensor gets power and ground, then look for a cut signal wire or a failed sensor.

Severity
High
Can I keep driving?
Yes, but with caution
Estimated cost
$40 to $400
Difficulty
Medium
System
Transmission
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0793 code means

Some transmissions, mostly those with six or more speeds and dual-clutch units, have a sensor on an intermediate shaft so the computer can monitor more precisely which clutches are applied.

The sensor generates pulses whose frequency depends on the speed or the quantity being measured. With no pulses, which is what the P0793 code reports, the computer cannot calculate the value and uses a substitute one.

Without this signal the computer loses information it needs to control the shifts, and it can switch to limp mode. See the guide to the input/output speed sensors for how they are tested.

First check that the sensor is getting power and ground. Then, with the component moving, measure the signal with an oscilloscope or with a multimeter on its frequency scale. If there are no pulses and the power is correct, the sensor is bad. If the pulses are there at the sensor but not at the computer, the wire is cut.

P0793 code symptoms

  • Check engine light on.
  • Transmission limp mode.

Likely causes of the P0793 code

  1. Sensor with no power. Check the fuse or the reference voltage.
  2. Signal wire cut between the sensor and the computer.
  3. Failed sensor. It does not generate pulses.
  4. Damaged reading element or tone wheel, with broken or dirty teeth.

How to diagnose the P0793 code step by step

  1. Read the sensor value on the scan tool and compare it with what is expected.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check power and ground with the key on: a correct reference and less than 0.1 V of drop on the ground.
  4. Measure the signal with the connector plugged in and see whether it changes with the condition.
  5. Do the wiggle test on the harness with the scan tool in graphing mode.
  6. Check the continuity of each wire up to the computer (under 1 ohm).

How to fix the P0793 code

  • Repair the connector or the wiring.
  • Replace the sensor if the tests confirm it.
  • Correct the real condition, if there is one.
  • Clear the codes and verify with a road test.

Technical reference data

  • Most are 3-wire Hall effect sensors.
  • These are approximate values: check the manufacturer data for your vehicle.

Brand-specific notes

This code appears on Honda and Hyundai transmissions and on some dual-clutch units.

P0793 on Honda

It shows up on Honda transmissions that carry an intermediate shaft speed sensor.

P0793 on Hyundai

It also appears on Hyundai transmissions, where the same connector and wiring checks apply before the sensor is replaced.

P0793 on Dual-Clutch Transmissions

Some dual-clutch units use this sensor to monitor which clutches are applied, so a missing signal here can send the transmission into limp mode.

Frequently asked questions about P0793

What does the P0793 code mean?
It is a generic OBD2 code that means the computer is getting no signal at all from intermediate shaft speed sensor A. It then uses a substitute value, and the transmission can go into limp mode.
Can I drive with a P0793 code?
Yes, with caution. With a P0793 code the transmission may go into limp mode, so keep trips short until it is repaired.
Does the sensor have to be replaced?
Only if the tests confirm it. The connector and the wiring fail just as often.
What does the intermediate shaft sensor do?
Some transmissions, mostly those with six or more speeds and dual-clutch units, have a sensor on an intermediate shaft. It lets the computer monitor more precisely which clutches are applied.
How much does it cost to fix P0793?
As a rough guide, between $40 and $400.
Will a P0793 code clear itself?
Not if the sensor is dead or a wire is cut. If the loss of signal was only a bad connection for a moment, the light can go out, but the code will probably return.
What is the most common cause of P0793?
A sensor with no power, a cut signal wire or a failed sensor. Check power and ground first, then the wiring, and replace the sensor last.

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