P0794 - Intermediate Shaft Speed Sensor A Circuit Intermittent
The P0794 code indicates an intermittent signal from the intermediate shaft speed sensor 'A', which monitors the rotational speed of the transmission's intermediate shaft. This sensor is critical for proper transmission shift timing and torque converter lockup. An intermittent circuit fault can cause erratic shifting, harsh engagement, or loss of power. Common causes include a faulty sensor, damaged wiring or connectors, or low transmission fluid level.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Erratic or harsh shifting
- Transmission slipping or delayed engagement
- Reduced fuel economy
2. Most Common Causes
- Faulty intermediate shaft speed (ISS) sensor with intermittent internal failure
- Damaged, corroded, loose, or intermittently contacting wiring or connectors in the ISS circuit
- Electrical noise or interference in the sensor circuit due to damaged shielding
- Broken, dirty, or damaged tooth on the intermediate shaft reluctor ring
- Intermittent internal failure in the TCM/PCM (uncommon)
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition.
Step 3: Visually check sensor wiring and connectors for damage or corrosion.
Step 4: Test sensor resistance and compare to manufacturer specs.
Step 5: Check for intermittent signal using a lab scope or graphing multimeter.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the intermittent signal can cause unpredictable shifting and potential transmission damage.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a DIY sensor replacement, or $150 to $300 if professionally diagnosed and repaired.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.