P0794Generic code

P0794 Code: Intermediate Shaft Speed Sensor A Intermittent

The P0794 code means the signal from intermediate shaft speed sensor A cuts out or jumps at times. The main effect is limp mode. Intermittent faults almost always come from a loose connection or a damaged wire, so look there first.

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 P0794 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. The intermittent dropouts behind the P0794 code are almost always caused by a loose connection or a damaged wire.

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.

Intermittent faults are found by reproducing them. With the engine running and the scan tool in graphing mode, move the wiring harness section by section, tap the connector gently and, if needed, warm the area with a hair dryer or wet the connector with a spray bottle. The spot where the reading jumps is where the fault is.

P0794 code symptoms

  • Check engine light on.
  • Transmission limp mode.

Likely causes of the P0794 code

  1. Loose contact in the connector, with pins that are loose or pushed back.
  2. Wire broken inside its insulation, which opens the circuit with vibration.
  3. Harness rubbing against moving or hot parts.
  4. Sensor with an intermittent fault, often related to temperature.

How to diagnose the P0794 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 P0794 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.

P0794 on Honda

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

P0794 on Hyundai

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

P0794 on Dual-Clutch Transmissions

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

Frequently asked questions about P0794

What does the P0794 code mean?
It is a generic OBD2 code that means the signal from intermediate shaft speed sensor A is cutting out or jumping intermittently. It is almost always a loose connection or a damaged wire.
Can I drive with a P0794 code?
Yes, with caution. With a P0794 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 P0794?
As a rough guide, between $40 and $400.
Will a P0794 code clear itself?
The light can go out while the connection behaves, but an intermittent fault usually returns. Finding the loose pin or damaged wire is the only way to fix it for good.
What is the most common cause of P0794?
A loose contact in the connector or a wire broken inside its insulation. Vibration and heat make the circuit open and close.

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