P0340 Code Meaning and Next Steps

First checks take 10 to 15 minutes for the first checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!The engine starts running much worse, stalls, or the warning light flashes.
!The vehicle begins to lose power sharply or misfire badly while the code is active.

If the light is steady and the vehicle still drives normally: Often yes for a short time, but it should not be ignored.

What to check first

Step-by-step checks

1
Safety first
Work with the engine off and cool enough to avoid burns from hot ignition and exhaust parts
2
Free - no tools
Inspect the cam sensor connector and harness for looseness, corrosion, or heat damage
3
Basic tool needed
Check whether the engine starts hard, runs rough, or sets related timing or misfire codes
4
Basic tool needed
If the code appeared after recent service, confirm the connector seating and harness routing first
5
Basic tool needed
If scan data is available, compare the cam signal to crank signal behavior before replacing parts

If the code returns

-If the signal changes when the harness is moved, wiring deserves a closer look than the sensor alone.
-If the engine still runs poorly after the visible checks, timing and mechanical synchronization become more important.
-If the code returns after a sensor swap, revisit the connector and signal path before buying another part.

Background

What this code means

P0340 is a generic OBD-II camshaft position signal code.

The fault can come from the sensor itself, its wiring, the connector, or a timing issue that makes the signal look wrong.

A rough idle, hard start, loss of power, or misfire can appear when the ECU cannot trust the cam signal.

Diagnosis

Common causes

Most common

Failed cam sensor

The sensor may drift, drop out, or stop reporting a believable signal.

Common

Connector or wiring issue

A loose, corroded, or heat-damaged connection can interrupt the signal.

Common

Timing or mechanical issue

A real timing problem can make the sensor appear faulty.

Possible

Reference or ground fault

The sensor may be fine but the circuit feeding it is not.

Avoid these mistakes

What not to do

xDo not replace sensors first if the wiring, connector, or mechanical timing side has not been checked.
xDo not ignore drivability changes just because the code sounds like a sensor or circuit problem.

Parts

Parts that may need replacing

PartTypical costNotes

Camshaft position sensor$30-$180Relevant when the signal tests poorly and the wiring checks out.

Connector pigtail repair$15-$90Worth checking if the plug or pins are damaged.

Timing belt/chain service part$100-$900Use only when timing evidence supports it.

Related OBD codes

P0341

P0341 usually means the bank 1 camshaft signal is outside the expected range or performance window.

P0342

P0342 usually means the bank 1 camshaft signal is reading too low.

P0344

P0344 usually means the bank 1 camshaft signal is intermittent or erratic.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0340 was expanded around common cam sensor circuit faults, including sensor failure, wiring issues, and connector problems.

This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.

This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.

Last reviewed: 2026-04-10

Reference: Open reference

P0340 - P0340 Usually Means the Bank 1 Camshaft Position Sensor Circuit Is Not Behaving Correctly