P0366: Camshaft sensor B signal out of range or unreliable (bank 1)

Camshaft position sensor B circuit range/performance, bank 1

Severity: Inspect soon

The computer relies on cam sensors to time fuel and spark, so a bad signal can cause stalling, rough running or no-start. CarParts.com calls it moderate and says it needs attention.

It gets more serious if:

Stop: Stop if the check engine light is flashing or the engine stalls repeatedly in traffic.

Source: how we rate severity

P0366 in short

P0366 means the computer sees an unreliable signal from the B camshaft sensor on bank 1, usually the exhaust cam. A bad sensor or wiring is the common cause; a damaged tone ring or engine problem is rarer. The car may run roughly or stall, so get it checked soon.

The cam position sensor tells the computer where the camshaft is, which it uses to time injectors, coils and variable valve timing. The B sensor on bank 1 is normally the exhaust cam sensor. P0366 sets when its signal is out of the expected range or does not agree with the crankshaft signal.

Wiring or connector faults, a failing sensor or a damaged tone ring or reluctor can cause it. A timing or mechanical problem inside the engine can also make the cam signal disagree with the crank.

GM has a note for P0341 or P0366 on several cars that says to replace the related cam sensor and retest, and to look at collision history if the code returns. Subaru has a bulletin that gives inspection steps for cam position and misfire codes on FA and FB engines.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

Cause 1: Faulty camshaft position sensor
Common general cause
Why it ranks here
CarParts.com lists a failing sensor among the main causes, and GM says to replace the related cam sensor and retest on the P0341 or P0366 cars it covers.
What would change this
Rises if the sensor reads erratic or a known-good sensor clears the code. Falls if the sensor and its wiring test normal.
How to test the camshaft position sensor
Cause 2: Damaged wiring or a poor connector at the sensor
Common general cause
Why it ranks here
Wiring problems are the first cause listed by CarParts.com.
What would change this
Rises if the connector is corroded, loose or the harness is chafed. Falls if the circuit tests normal.
Cause 3: Damaged tone ring or an internal timing problem
Possible — needs testing
Why it ranks here
CarParts.com lists a damaged tone ring and internal engine problems. Subaru has a bulletin covering cam position and misfire codes on FA and FB engines, but only the summary was read.
What would change this
Rises if cam and crank timing do not correlate or the ring is damaged. Falls if timing checks out.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Read all stored codes and note whether other cam or crank sensor codes, or misfire codes, are stored with P0366.
Low risk
- IfP0341 or another cam code is stored with it on a GM car
  It meansGM says to replace the related cam sensor and retest.
  Go to step 2
- IfMisfire codes are also stored on a Subaru FA or FB engine
  It meansAsk the dealer about the Subaru cam position bulletin.
  Go to step 2
- IfP0366 is the only code
  It meansInspect the wiring and sensor.
  Go to step 2
Step 2: Look at the cam sensor connector and harness for corrosion, damage or a loose fit.
Low risk
- IfThe connector or harness is damaged
  It meansRepair the wiring, then clear the code and recheck.
  Points to: Damaged wiring or a poor connector at the sensor
- IfWiring looks fine
  It meansHave the sensor and signal tested.
  Go to step 3
Step 3: Have a shop check the cam sensor signal against the crank signal and replace the sensor if it is faulty, then check the tone ring.
Best left to a shopTool: scan tool, scope
Warning:Checking the tone ring and timing may mean removing engine parts. Leave that to a shop.
- IfThe sensor signal is erratic or a new sensor clears the code
  It meansThe sensor was at fault.
  Points to: Faulty camshaft position sensor
- IfA new sensor does not help and timing does not correlate
  It meansThe tone ring or an internal timing problem is likely.
  Points to: Damaged tone ring or an internal timing problem

Symptoms

Check engine light on
Hard starting or a no-start
Rough running or stalling Gets more serious: stop and have it checked.
Lower fuel economy

Compare with: Rough idle with the check engine light on

How to fix

Step 1: With the engine off and cool, look at the cam sensor connector and wiring for damage or a loose plug.
Step 2: Ask a dealer whether your VIN has a bulletin for P0366.

Parts and cost context

Camshaft position sensor:Test the wiring and signal before buying a sensor. Labor varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Subaru

2013 · BRZ
Supported by vehicle data
Subaru bulletin 11-130-13R covers cam position and misfire DTCs including P0366 on the FA engine. The steps were not read.
2013 · Crosstrek
Supported by vehicle data
Subaru bulletin 11-125-12 names P0366 with cam position and misfire codes. Whether the bulletin is still current is not verified.

11-130-13RStatus unverified
Cam position or misfire DTCs including P0365 and P0366
2013brz · NHTSA 10089963
Inspection and repair procedures for FA and FB engines. The NHTSA summary does not give the steps.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
11-125-12Status unverified
DTCs P0365, P0366, P0390, P0391 and misfire P0301 to P0304
2013crosstrek · NHTSA 10093944
Cam position and misfire code bulletin. The NHTSA summary does not give the steps.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Cadillac

2008 · CTS
Supported by vehicle data
GM PIP4333 names P0366 with cam timing and position codes on 3.6L LY7/LLT engines. Whether the bulletin is still current is not verified.

PIP4333Status unverified
DTCs P0011, P0014, P0021, P0024, P0341, P0346, P0366 or P0391 (3.6L)
2008cts · NHTSA 10024623
Names P0366 with cam timing and position codes on 3.6L LY7/LLT. The summary does not give the repair.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

All Ignition and engine position sensors codes

P0366 questions

What is the B camshaft sensor?

On most engines, the B sensor on bank 1 is the exhaust camshaft sensor. Your service information shows exactly where it is on your engine.

Should I replace the sensor right away?

Check the wiring and connector first. GM does say to replace the cam sensor and retest on some cars, but a wiring fault would not be fixed by a new sensor.

Sources and review

P0366 Code: Camshaft Position Sensor B Circuit Range / Performance Bank 1 — CarParts.com Research Team
PIP5329A: P0341 and/or P0366 set — General Motors
11-130-13R: Cam position or misfire DTCs including P0365 and P0366 — Subaru
11-125-12: DTCs P0365, P0366, P0390 and P0391; misfire DTCs P0301 to P0304 — Subaru
PIP4333: DTCs P0011, P0014, P0021, P0024, P0341, P0346, P0366 or P0391 with 3.6L LY7 or LLT — General Motors

Last reviewed: October 15, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Inspect soon

Most likely causes

Cause 1: Faulty camshaft position sensor

Cause 2: Damaged wiring or a poor connector at the sensor

Cause 3: Damaged tone ring or an internal timing problem

What to test first

Step 1: Read all stored codes and note whether other cam or crank sensor codes, or misfire codes, are stored with P0366.

Step 2: Look at the cam sensor connector and harness for corrosion, damage or a loose fit.

Step 3: Have a shop check the cam sensor signal against the crank signal and replace the sensor if it is faulty, then check the tone ring.