OBD-II Car P0340 Error
What it means
P0340 is a generic OBD-II code meaning 'Camshaft Position Sensor 'A' Circuit Malfunction.' The camshaft position sensor (CMP) tells the engine computer (PCM) the exact position of the camshaft so it can time the spark and fuel injection. P0340 sets when the PCM loses or cannot make sense of the CMP signal, which disrupts ignition and injector timing.
The bottom line on the P0340 error
P0340 is a camshaft position sensor circuit fault, and the usual culprit on higher-mileage engines is a failing sensor or one soaked in oil from a leaking valve cover gasket, not the wiring. Take it seriously โ a lost cam signal can stall the engine or cause a no-start, riskier than most sensor codes.
Start cheap: reseat the connector, clean off any oil, and repair a chafed wire before buying parts. If wiring is good and the sensor tests bad, a new CMP sensor ($20โ$100) fixes most cases; only a returning code points to a stretched timing chain or reluctor ring.
P0340 snapshot
Our own at-a-glance triage of the P0340 error, from the verified data on this page. See error-code rankings โ ยท How we score โ
Common causes of the P0340 error
- Faulty or failing camshaft position sensor
- Loose, corroded, or damaged sensor connector or wiring (open or short circuit)
- Oil contamination on the sensor from a leaking valve cover gasket
- Damaged reluctor / tone ring that the sensor reads
- Stretched or worn timing chain (or jumped timing belt) throwing off cam-to-crank timing
- Faulty PCM (rare)
Which OBD-II cars get the P0340 error
P0340 is a generic code that shows up across almost every make โ it's common on high-mileage Nissan (Altima, Cube, Sentra), Ford (Focus, Freestar), Chevrolet, Dodge, and Toyota engines, and on many 4-, 6-, and 8-cylinder engines once the sensor or its wiring ages past roughly 80,000โ120,000 miles. Engines with a leak-prone valve cover gasket (which soaks the sensor in oil) are especially prone to it.
How to fix the OBD-II Car P0340 error
- 1Inspect the sensor connector and wiringLocate the camshaft position sensor and check its connector for looseness, corrosion, or bent pins. Inspect the wiring for chafing, breaks, or shorts. Reseat the connector and repair any damaged wire โ a poor connection alone can set P0340.
- 2Check for oil contaminationOn higher-mileage engines, a leaking valve cover gasket can soak the sensor in oil and disrupt its signal. Clean the sensor, and fix the leak so it does not recur.
- 3Test the sensorWith a multimeter (and the wiring diagram for your vehicle), check for the reference voltage and ground at the connector with the ignition on. A sensor that fails its spec should be replaced with an OEM-quality part.
- 4Replace the camshaft position sensorIf wiring is good and the sensor tests bad, fit a new sensor, clear the code, and retest. This resolves a large share of P0340 cases.
- 5Verify engine timing if the code persistsIf the code returns after a known-good sensor and wiring, the issue may be a stretched timing chain or a reluctor ring problem causing the cam and crank signals to disagree. This needs deeper diagnosis.
๐งฐ When to call a professional
Call a professional if the engine cranks but will not start, if the code returns after replacing the sensor and checking the wiring, or if you suspect a timing chain or reluctor ring problem. Diagnosing cam-versus-crank timing and internal timing components requires a scan tool and mechanical expertise.
OBD-II P0340 vs OBD-II P0011 vs OBD-II P0325: how they compare
How this code stacks up against related error codes for difficulty, urgency, and cost.
| OBD-II P0340 | OBD-II P0011 | OBD-II P0325 | |
|---|---|---|---|
| DIY difficulty (1โ5) | 3 | 3 | 3 |
| Urgency (1โ5) | 4 | 3 | 3 |
| Typical cost | $$ | $$ | $$ |
How much does it cost to fix the P0340 error?
| DIY parts / self-fix | $20โ$100 (sensor only) |
| Professional repair / service | $120โ$323 |
| Replacement (new unit) | N/A โ repair, don't replace the car |
Repair or replace?
This is almost always a repair, not a reason to replace the vehicle. A camshaft position sensor is a $20โ$100 part and a common shop bill runs $120โ$300 including labor, which is trivial next to a car's value. The only time cost climbs is if the underlying problem turns out to be a stretched timing chain or reluctor ring โ a several-hundred-to-thousand-dollar job โ but even then it's fixable, so diagnose the true cause before spending big.
Common replacement parts for the P0340 error
| Camshaft position sensor (CMP) | $20โ$100 | OEM-quality recommended; the fix for most P0340 cases | |
| Sensor connector / pigtail | $10โ$30 | for corroded or damaged connectors | |
| Valve cover gasket | $15โ$60 | only if an oil leak is contaminating the sensor |
Prices are typical retail ranges and vary by model and supplier โ always confirm the exact part number for your appliance before buying.
OBD-II P0340 error โ FAQ
๏ผ โ Is it safe to drive with a P0340 code?
It is risky. The car may start and run, but a failing camshaft sensor can cause stalling, hard starting, hesitation, and sudden no-start conditions โ which is dangerous in traffic. Drive only as far as needed to get it diagnosed, and be prepared for a possible stall.
๏ผ โ How much does it cost to fix P0340?
A camshaft position sensor itself is usually $20โ$100, with total replacement commonly around $120โ$300 including labor. Wiring repairs are cheaper, while a timing chain or reluctor ring problem can cost significantly more.
๏ผ โ Can a P0340 code keep my car from starting?
Yes. The PCM uses the camshaft signal to time spark and fuel. If that signal is lost entirely, the engine may crank but fail to start, or it may start and then stall.
Sources & manufacturer references
This guide is independently written and not affiliated with OBD-II. Always unplug appliances before servicing and follow your model's manual. Error codes and steps can vary by model โ when in doubt, consult a qualified technician.