P0340 Camshaft Position Sensor "A" Circuit (Bank 1)
P0340 is a generic OBD2 powertrain code. It means “Camshaft Position Sensor "A" Circuit (Bank 1)” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Ask the AI about P0340 on your car- System
- Powertrain (P)
- Code type
- Generic (SAE)
- Range
- P03xx
- Urgency
- Moderate
What P0340 means
The camshaft position sensor tells the computer where the camshaft is, so it can time injection and ignition to each cylinder’s stroke. The computer found no signal or a circuit fault (P0340 on bank 1, P0345 on bank 2), or a signal that doesn’t make sense (P0341).
Symptoms
- Long cranking or hard starting
- Rough running or misfires
- Occasional stalling
- Reduced power
Most likely causes
- A failed sensor
- A damaged connector or wiring
- A weak battery or slow cranking (enough to set P0340 on some cars)
- Timing chain or belt problems — especially behind P0341
What to check first
- Check the battery and cranking speed first
- Inspect the sensor’s connector and wiring
- Test the sensor’s signal; if it’s good, have the timing checked
Can I keep driving with P0340?
Drivable — plan the repair soon
Usually yes, to the workshop — many engines keep running on the crankshaft signal alone — but the car may stall or refuse to restart, so don’t plan long trips.
What the wording tells you
The wording names a fault in the component’s circuit without saying more. Check the connector, the wiring and the fuse, and test the component, before replacing it.
Bank 1: engines with two rows of cylinders — V6, V8, boxer — have two banks. Bank 1 is the side that holds cylinder 1, bank 2 the other side; an inline engine has only bank 1.
Camshaft “A”: by the SAE convention “A” is the intake (or left/front) camshaft and “B” the exhaust (or right/rear) one — here, the intake camshaft.
How P0340 breaks down
Powertrain. Engine, transmission, fuel and emissions — the codes behind the check engine lamp.
Generic code: defined by SAE, the same on every make.
Ignition system & misfire.
The specific fault within this range.
Where to look: Ignition system & misfire
Misfire detection, ignition coils, crankshaft and camshaft position sensors and knock sensors. The engine computer detects misfires from dips in crankshaft speed, so this area often reports a problem that starts elsewhere — in the fuel supply or in compression.
All P03xx codes →Ask the AI about P0340 on your car
Pick your car and ask — the assistant takes your make, model and engine into account. Ten questions a day, free, no sign-up.
The assistant is answering…
That's 10 for today
The free web limit resets tomorrow. In the Brimly app the assistant knows your specific car — its real mileage, fuel log, and service history.
Requires iOS 18.1 or later. Free to download, with optional in-app purchases.
The conversation is stored only in your browser — we don't keep it on our servers.
Read and clear P0340 on your iPhone
Brimly reads stored, pending and permanent codes through a Bluetooth LE or Wi-Fi OBD2 adapter, explains each one offline from the same 2,693-code dictionary as this page, and clears them once the fault is fixed — each clear goes into the car’s service history with the codes it removed. OBD diagnostics are part of Brimly Forever, a one-time purchase; the PRO assistant explains a code for your exact car.
Requires iOS 18.1 or later. Free to download, with optional in-app purchases.
Frequently asked
What does P0340 mean?
P0340 is a generic OBD2 powertrain code. It means “Camshaft Position Sensor "A" Circuit (Bank 1)” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker. The camshaft position sensor tells the computer where the camshaft is, so it can time injection and ignition to each cylinder’s stroke. The computer found no signal or a circuit fault (P0340 on bank 1, P0345 on bank 2), or a signal that doesn’t make sense (P0341).
Can I drive with P0340?
Usually yes, to the workshop — many engines keep running on the crankshaft signal alone — but the car may stall or refuse to restart, so don’t plan long trips.
What causes P0340?
A failed sensor; A damaged connector or wiring; A weak battery or slow cranking (enough to set P0340 on some cars); Timing chain or belt problems — especially behind P0341.
How do I clear P0340?
Fix the cause first, then clear it with any OBD2 scanner or app. Once the fault is gone the car also clears it on its own: the check engine lamp goes off after the self-test passes on three drive cycles in a row, and the stored code ages out after about 40 warm-ups. Clearing without a repair only hides it for a while — and resets the readiness monitors an emissions inspection looks at.
Is P0340 the same on every car?
Yes. P0340 is a generic SAE J2012 code, so its definition is identical on every make and model. What differs is the cause behind it and the repair procedure, which depend on the engine — that’s why the assistant on this page asks for your car.
Guides
Definitions: the generic SAE J2012 codes from Brimly’s offline dictionary (data version 2026.09). Causes and advice are general guidance for all makes — the service information for your car has the last word.