P2749
Intermediate Shaft Speed Sensor C Circuit
Transmission controls
Generic OBD-II
Medium
What it means
P2749 sets when the intermediate shaft speed sensor C circuit has a fault. The transmission controller uses this speed signal to time shifts and torque-converter lockup, so a lost or erratic signal can cause harsh or wrong shifts, wrong-gear-ratio codes, and failsafe mode. The engine starts and runs normally.
Medium
Can I keep driving? Often yes but shifting may be erratic — losing a transmission speed signal can trigger harsh shifts or failsafe mode. Get it checked soon.
Common symptoms
What you'll notice
- Check-engine light on
- Harsh, erratic, or incorrect gear shifts
- Transmission entering failsafe/limp mode
- Possible gear-ratio or speedometer-related codes
Common causes
Most likely first
- Faulty intermediate shaft speed sensorLikely
- Open, shorted, or corroded sensor wiring or connectorCommon
- Poor electrical connection at the sensorCommon
- Metal debris or damage at the sensor tip or tone ringLess often
- Faulty TCM/PCM (least likely)Less often
How to diagnose & fix
Work through it in order
- Scan for related codes (P2748, P2750, P2751) and read freeze-frame.
- Inspect the speed sensor connector and wiring for damage or corrosion.
- Check the sensor and its mounting for debris or damage.
- Measure the sensor's output or resistance against spec.
- Replace the speed sensor if faulty; verify wiring and the module last.
FAQ
Quick answers
Is it safe to drive with P2749?+
You can usually drive to a shop, but shifts may be harsh or unpredictable. Avoid long trips until it's fixed to reduce transmission wear.
Can I just clear P2749?+
It returns until the sensor or its wiring is repaired.
Related codes
Often seen with P2749
Read & clear P2749 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX