P2748: Intermediate Shaft Speed Sensor B Circuit Intermittent
The P2748 code indicates an intermittent signal from the intermediate shaft speed sensor B, 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 transmission slippage. Common causes include a faulty sensor, damaged wiring or connectors, low transmission fluid, or internal transmission issues.
1. Most Common Causes
- Loose, corroded, or damaged terminals in the intermediate shaft speed sensor 'B' connector
- Damaged wiring in the signal, ground, or reference circuit (intermittent short or open due to vibration)
- Internally defective intermediate shaft speed sensor 'B' (thermal or mechanical failure)
- Excessive clearance or damage to the intermediate shaft reluctor ring
- Internal TCM/PCM failure (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Erratic or harsh shifting
- Transmission slipping or delayed engagement
- Reduced fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect sensor B wiring and connector for damage, corrosion, or loose connections.
Step 3: Test sensor resistance and voltage output per manufacturer specs.
Step 4: Check transmission fluid level and condition; top off or replace if necessary.
Step 5: If sensor and wiring are OK, perform a transmission mechanical inspection.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as intermittent sensor signals can cause transmission damage. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically $50-$150 for sensor replacement, but costs may increase if wiring repairs or transmission work is needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.