Engine

P1340 — Camshaft Position Sensor B Circuit Malfunction

Severity: medium Drive with care, to a shop

What P1340 means

P1340 is a manufacturer-specific code, but it most often means the engine computer sees a bad signal from camshaft position sensor B or its circuit. The computer uses this signal to know which stroke each cylinder is on, which sets ignition timing and fuel injection. When the signal drops out or disagrees with the crankshaft sensor, the engine loses synchronization.

Symptoms

  • Hard starting or long cranking
  • Rough idle
  • Engine stalling
  • Check Engine light on
  • Loss of power and hesitation
  • Higher fuel consumption

Possible causes

  1. Failed camshaft position sensor B
  2. Damaged wiring or connector, including under the valve cover
  3. Stretched timing chain or off-set cam timing
  4. Faulty variable valve timing actuator or solenoid
  5. Damaged camshaft reluctor wheel or target
  6. Low battery voltage
  7. Faulty engine control module (rare)

How to diagnose

  1. Scan all codes and freeze-frame data, noting related crankshaft or misfire codes.
  2. Inspect the sensor, connector and harness for oil, chafing, corrosion or breaks.
  3. Test sensor power, ground and signal wire with a multimeter using the wiring diagram for your model.
  4. Check battery voltage and engine ground quality.
  5. Compare camshaft and crankshaft signals on a scope.
  6. Check oil level and condition, and the VVT solenoid and phaser operation.
  7. Assess the timing chain: noise, slack and cam-to-crank correlation.
  8. If the sensor is suspect, replace it, clear the code and see whether it returns.

Common fixes

  • Replace camshaft position sensor B
  • Repair the wiring or connector, or replace the damaged harness section
  • Replace the timing chain or belt with tensioners and set the timing
  • Clean or replace the VVT solenoid and change to the correct oil
  • Replace a damaged camshaft target wheel

P1340 on different brands

Ford · manuals
Ford defines it as an improper operation of the camshaft position sensor B circuit.
Honda · manuals
Honda ties it to the ignition control module (ICM) and cylinder identification or synchronization.
Hyundai · manuals
Hyundai lists it as "IFS 2 Open", an open condition in that circuit.
Jaguar
Jaguar defines it as a camshaft position sensor B circuit fault.
Mazda · manuals
Mazda defines it as an improper operation of the camshaft position sensor B circuit.
Mercedes-Benz · manuals
Mercedes-Benz lists it as a fault in the camshaft position (CMP) sensor signal.
MINI
MINI defines it as multiple-cylinder misfire during start.
Porsche
Porsche describes it as the timing chain being out of position on bank 1.

Questions and answers

Can I drive with P1340?

Only a short distance to get it diagnosed. The engine may stall or hard-start, and if cam timing is off it can damage the engine.

What most often causes P1340?

Usually a failed camshaft sensor or damaged wiring to it. If a new sensor doesn't fix it, check the timing chain and the VVT system.

Does P1340 mean the same thing on every brand?

No. It is a manufacturer-specific code. Ford, Jaguar and Mazda describe it as the sensor B circuit, while Honda, Hyundai, MINI and Porsche define it differently, so check the spec for your make.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.