Engine

P0340 — Camshaft Position Sensor Circuit Malfunction (Bank 1)

Severity: medium Drive with care, to a shop

What P0340 means

The engine control unit compares the camshaft sensor signal with the crankshaft sensor signal to know which stroke each cylinder is on. This timing information is needed for sequential fuel injection and ignition. P0340 sets when the bank 1 camshaft signal is missing, erratic or does not match what the ECU expects.

Symptoms

  • Check Engine light on
  • Rough or unstable idle
  • Hard starting or no start
  • Engine stalling
  • Reduced power and sluggish acceleration
  • Poor fuel economy
  • Other cam/crank correlation or timing codes alongside

Possible causes

  1. Failed camshaft position sensor
  2. Damaged wiring or corroded connector at the sensor
  3. Faulty crankshaft position sensor causing a signal mismatch
  4. Stretched timing chain or worn belt, or jumped timing
  5. Oil contamination on the sensor or connector
  6. Power or ground supply problem to the sensor
  7. Failed ECM (uncommon)

How to diagnose

  1. Scan all codes and freeze-frame data; note any crankshaft sensor or timing correlation codes
  2. Inspect the sensor, connector and harness for chafing, corrosion, oil and a loose fit
  3. Check sensor power, ground and reference voltage at the connector using the wiring diagram
  4. Test the wiring for opens, shorts to ground or shorts to voltage back to the ECU
  5. Compare camshaft and crankshaft signals with a scope
  6. Test the sensor itself (inductive or Hall type) and check its mounting and air gap
  7. Evaluate timing chain or belt condition and cam timing using scan data for cam variance
  8. If all is good, check the ECM and its power supply

Common fixes

  • Replace the camshaft position sensor
  • Repair the wiring or replace the connector, and clean the terminals
  • Replace the crankshaft sensor if it tests bad
  • Correct the timing issue by replacing the chain or belt and setting timing
  • Repair the supply circuit or replace the ECM once confirmed

P0340 on different brands

Ford · manuals
On Ford, the extended P0340:01 format refers to the intake cam position circuit, bank 1; it identifies the monitor condition that was detected, not a confirmed failed part.

Questions and answers

Can I drive with a P0340 code?

Only briefly and carefully, such as to a repair shop. The engine may stall or not restart, and the risk of damage is higher if timing components are the cause.

What most often causes P0340?

Usually the camshaft sensor itself or its wiring and connector. If those check out, look at the crankshaft sensor and the timing chain or belt.

Will replacing the sensor fix it?

Not always. Check the wiring, connector, power supply and any oil contamination first, or the code may return.

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.