What P0340 means
The engine computer isn't getting a usable signal from the camshaft position sensor on bank 1. It uses that signal to know which cylinder is about to fire and to control variable valve timing. A failing sensor or a corroded connector is the most common cause.
How the engine computer detects it
The camshaft position sensor, almost always a Hall sensor, tells the engine module which stroke cylinder 1 is in – one crank revolution alone is ambiguous – and measures the actual cam phase with variable timing. Sensor A is the intake camshaft, bank 1 the side with cylinder 1. P0340 means no or too few cam pulses arrive while the crankshaft turns in sync. GM sets it after 5.5 s (or 4 s) of cranking without a cam pulse or fewer than 4 pulses in 3 s running, gasoline engines after two trips. Ford checks the ratio of cam to crank events from 200 rpm. The engine usually keeps running but starts longer and loses power as cam timing is held. Bulletins: corroded connectors on GM V8s (PIP5335C), moisture in the oil on short trips in Ford hybrids (SSM 48598).
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Longer cranking before the engine starts
- Loss of power (cam timing held in its base position)
- Rough idle, occasionally stalling
Common causes
- Camshaft position sensor faulty (heat, moisture) Most likely
- Connector or wiring corroded or open, 5 V reference disturbed Most likely
- Tone wheel on the camshaft or phaser damaged, loose or at the wrong distance Possible
- Timing drive jumped or wrongly assembled Possible
- Moisture in the engine oil from short trips (Ford hybrids) Less likely
How to diagnose P0340
- With the ignition off, unplug the sensor and check the connector and wiring for corrosion, oil or broken wires.
- Check for other sensor codes. Several at once can mean a shared 5-volt sensor supply is shorted.
- If cam and crank correlation codes such as P0016 are also set, or the engine rattles at startup, the timing chain may have stretched or jumped. Have that checked before replacing parts.
- A shop can watch the sensor signal on a scanner or scope while the engine cranks.
- Replace the sensor if the wiring is good. On many engines it's bolted to the cylinder head or timing cover.
- If a new sensor doesn't fix it, the toothed wheel on the camshaft may be damaged or loose.
Vehicles that report P0340 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Infiniti G35 | 2003–2004 | 6 | 81k | |
| Nissan Altima | 2003–2016 | 6 | 118k | |
| Nissan Murano | 2003–2007 | 6 | 107k | |
| Nissan 350Z | 2003 | 5 | 94k | |
| Nissan Maxima | 2003 | 5 | 91k | |
| Chevrolet Silverado 1500 | 2002–2021 | 3 | — | |
| Infiniti I35 | 2003–2004 | 3 | 60k | |
| Mercedes-Benz C250 | 2012–2013 | 3 | — | |
| Ford Ecosport | 2018–2020 | 3 | — |
Counts of owner complaints to the NHTSA that mention P0340 (85 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 3
- Ignition system or misfire
- 40
- Specific fault
Questions drivers ask
Can I drive with code P0340?
Usually yes, for short trips, because most engines keep running on the crankshaft sensor alone. Expect longer cranking and less power, and the engine may not restart after you shut it off. If it stalls while driving, stop using it and have it towed.
Will my car pass an emissions inspection with P0340?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0340 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P0340 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: easy. Start with the cheapest checks before replacing expensive parts.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0340. They can point to a shared cause, so it's worth checking them together.
- P0344Camshaft Position Sensor A Circuit Intermittent Bank 1 or Single Sensor8 complaints
- P0365Camshaft Position Sensor B Circuit Bank 16 complaints
- P0014"B" Camshaft Position - Timing Over-Advanced or System Performance (Bank 1)3 complaints
- P0299Turbocharger/Supercharger A Underboost Condition3 complaints
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.