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 intermediate shaft inside the transmission. The PCM uses this data to control shift timing and torque converter lockup. A loss of signal can cause erratic shifting, harsh engagement, or transmission slippage. Common causes include a faulty sensor, damaged wiring or connector, low transmission fluid, or internal transmission mechanical failure.
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 or damaged intermediate shaft speed sensor (ISS)
- Open or short-to-ground/battery in the sensor signal circuit
- Loose, corroded, or damaged sensor connector terminals
- Damaged, dirty, or misaligned intermediate shaft reluctor ring
- Internal TCM/PCM failure (rare)
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition; top up or replace if necessary.
Step 3: Visually inspect the intermediate shaft speed sensor and its wiring/connector for damage, corrosion, or loose connections.
Step 4: Test the sensor's resistance and voltage output using a multimeter; compare to manufacturer specifications.
Step 5: If sensor and wiring are okay, check for internal transmission issues (requires professional diagnosis).
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can cause transmission damage due to improper shifting or slipping. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost to fix P0793 typically ranges from $150 to $400, including parts and labor. Sensor replacement is usually $50-$150 for the part and $100-$250 for labor, but internal transmission repairs can be much higher.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.