What it means
Timing reference signal B delivers more pulses per crank revolution than expected — typically electrical noise, missing reluctor gap, or wrong tone wheel.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine control module counts pulses from timing reference signal B to determine crankshaft position. This code sets when it detects more pulses per crank revolution than expected, which can result from electrical noise, a faulty sensor or circuit, or a damaged or incorrect tone wheel.
Common causes
Most likely first.
- Electrical interference or a noisy signal
- Damaged or incorrect tone wheel
- Faulty timing reference sensor or wiring
Symptoms
- Check engine light on
- Rough or uneven engine running
- Stalling or hard starting
- Power loss
How to diagnose it
- Record freeze-frame data and review live engine-speed data while cranking and at idle to see when the extra pulses occur.
- Locate signal B using the wiring diagram, then inspect its wiring and connector for loose contacts, corrosion, damaged insulation, or routing beside interference sources.
- Check that the installed signal B sensor and tone wheel are the correct parts and are securely mounted.
- Examine the tone wheel for damage or a missing reference gap that could produce extra transitions.
- Use an oscilloscope or suitable scan-tool waveform display to compare signal B's pulses with the manufacturer's specification and check for electrical noise.
Common fixes
- Secure or reroute signal B wiring away from sources of electrical interference.
- Clean and reconnect a loose or corroded signal B connector.
- Repair damaged signal B wiring or its shielding where fitted.
- Replace a faulty signal B sensor or incorrect or damaged tone wheel after confirming the cause.
Can I keep driving?
Avoid driving if the engine stalls, hesitates severely, or loses power, since the fault can disrupt engine timing and leave you stranded. If symptoms are mild, limit driving and arrange prompt diagnosis.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.