P0793 - Intermediate Shaft Speed Sensor A Circuit No Signal
The P0793 code indicates that the Powertrain Control Module (PCM) has detected no signal from the intermediate shaft speed sensor (also known as the input shaft speed sensor) on circuit A. This sensor monitors the rotational speed of the transmission's intermediate shaft, which is critical for proper shift timing and torque converter lockup. A loss of signal can cause the transmission to shift erratically or go into limp mode.
01. Most Common Causes
- Faulty intermediate shaft speed sensor
- Damaged or corroded wiring/connectors to the sensor
- Low transmission fluid level or contaminated fluid
- Internal transmission mechanical failure
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission stuck in limp mode (e.g., only 2nd gear)
- Decreased fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition; top up or replace if necessary.
Step 3: Visually check the sensor wiring and connector for damage, corrosion, or loose connections.
Step 4: Test the sensor's resistance and voltage output using a multimeter; compare to manufacturer specs.
Step 5: If sensor and wiring are OK, check for internal transmission issues (e.g., damaged tone wheel) via scope or professional diagnosis.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0793 can cause erratic shifting, transmission damage, or sudden loss of drive. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs vary: sensor replacement $150-$300, wiring repair $100-$200, or internal transmission work $1,000+. Diagnostic fee is typically $100-$150.