P1340
System
Powertrain (Ignition)
Scanner required
Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Camshaft Position Sensor B Circuit Malfunction

Understand P1340, common causes, and the right TOPDON scanner to diagnose it.

Camshaft position sensor B circuit fault — ignition timing reference affected.

Common symptoms

  • Hard start
  • Rough idle
  • Stalling

Typical causes

  • Failed cam sensor B
  • Wiring in valve cover
  • Timing chain noise

What scanner do you need?

Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.

Diagnostic tips

  • Record freeze frame data when the code first sets
  • Clear the code only after fixing the root cause
  • Check for related pending codes that point to a common issue
  • Verify battery voltage is above 12.4V before chasing sensor codes

Recommended TOPDON scanners

Frequently asked questions

Can I diagnose P1340 with a basic code reader?
P1340 may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Is it safe to drive with P1340?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.