P2748 — Intermittent fault in intermediate shaft speed sensor circuit

The code indicates a problem with the intermediate shaft speed sensor B circuit, which monitors rotational speed inside the transmission. An intermittent signal means the sensor or its wiring is sending inconsistent data to the engine control unit.

Common causes

The cause is almost always one of a few things. Here they are — P2748 rarely comes from anything outside this list:

• Faulty intermediate shaft speed sensor
• Damaged or corroded wiring/connectors
• Loose or poor electrical connections
• Internal transmission issues affecting sensor
• ECU software glitches or faults

Where to start

In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:

1. Check and clean sensor connectors and wiring
2. Inspect wiring harness for damage or corrosion
3. Test sensor output with diagnostic tools
4. Replace faulty intermediate shaft speed sensor
5. Address internal transmission repairs if needed

That is what holds for P2748 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.