Open in the ground circuit to the camshaft position sensor. Open in the signal circuit between the sensor and the PCM. Signal circuit shorted to 5 volts (listed by OBD-Codes.com). Failed camshaft position sensor, such as one internally shorted to voltage (OBD-Codes.com calls this occasional; RepairPal's most common repair is sensor replacement). Broken tone ring (reluctor wheel), the toothed ring the sensor reads (listed by RepairPal). Engine computer (PCM) failure, which is less likely.

Clean and repair corroded or damaged connector terminals. Repair an open ground or signal wire, or a signal wire shorted to voltage. Apply a PCM software update if a TSB covers your vehicle. Replace the camshaft position sensor (RepairPal's most common repair for this code). Repair a broken tone ring if inspection finds one. Diagnose and replace the PCM only after the wiring and sensor check out.

P0343🔧 Engine management / camshaft position sensorStop and fix promptly

P0343: Camshaft Position Sensor A Circuit High, Bank 1 (Meaning, Causes, Fixes)

Q: Can I keep driving with P0343?

Stop and fix promptly. Get this diagnosed promptly. RepairPal rates P0343 'Urgent' and lists an engine that may not start among the symptoms, and OBD-Codes.com says the engine may die out, or run fine until it's shut off and then not restart. If the engine bucks, surges or stalls, avoid relying on the car in traffic or on the highway until it's checked.

Reviewed 2026-10-24 · Based on 2 cited source(s)

What P0343 means

The camshaft position sensor (CMP) reports the rotational position of the camshaft. RepairPal explains that the engine computer (PCM) uses this signal to control the fuel injectors and ignition coils. OBD-Codes.com adds that the PCM uses it to confirm the crankshaft sensor signal is timed to cylinder 1 and to synchronize the start of fuel injection. OBD-Codes.com defines P0343 as a generic code, 'Camshaft Position Sensor A Circuit High Input (Bank 1)', and describes it as an electrical circuit fault in the bank 1 cam sensor's incoming signal, typically at engine start-up. Bank 1 is the side of the engine that contains cylinder 1. OBD-Codes.com says the code seems more common on VW, Kia, Hyundai, Chevrolet, Toyota and Ford vehicles, and that it only sets on Hall effect sensors (usually three wires), not two-wire magnetic pickup sensors. Note where the sources differ: RepairPal's title doesn't mention a bank, and its explanation (the PCM sets the code on an irregular signal or no signal) is the same wording it uses for other camshaft sensor codes such as P0342 and P0345. The cause lists also differ: OBD-Codes.com focuses on wiring (an open ground or signal wire, or a signal wire shorted to 5 volts) and calls a faulty sensor only occasional, while RepairPal lists a broken tone ring, sensor failure, PCM failure and wiring, with sensor replacement as its most common repair. The bank 2 version of this code is P0348. Related codes are P0340 (circuit), P0341 (range/performance), P0342 (circuit low) and P0344 (intermittent); OBD-Codes.com notes P0340 or P0341 may be stored along with P0343.

Severity: can I keep driving?

Stop and fix promptly

Get this diagnosed promptly. RepairPal rates P0343 'Urgent' and lists an engine that may not start among the symptoms, and OBD-Codes.com says the engine may die out, or run fine until it's shut off and then not restart. If the engine bucks, surges or stalls, avoid relying on the car in traffic or on the highway until it's checked.

Common symptoms

Check engine light on
Bucking or surging (listed by OBD-Codes.com)
Engine dies out, but may restart if the problem comes and goes
Runs fine until restarted, then won't restart, or the engine may not start
Decreased engine performance or increased fuel consumption (listed by RepairPal)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Open in the ground circuit to the camshaft position sensor
Open in the signal circuit between the sensor and the PCM
Signal circuit shorted to 5 volts (listed by OBD-Codes.com)
Failed camshaft position sensor, such as one internally shorted to voltage (OBD-Codes.com calls this occasional; RepairPal's most common repair is sensor replacement)
Broken tone ring (reluctor wheel), the toothed ring the sensor reads (listed by RepairPal)
Engine computer (PCM) failure, which is less likely

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Read and write down all stored codes and freeze frame data. If P0340, P0341 or crankshaft position codes are also stored, mention them, since they change where to look.
Search for technical service bulletins (TSBs) for your vehicle first. OBD-Codes.com notes the manufacturer may have a PCM reprogram for this issue.
Locate both the camshaft and crankshaft position sensors (your repair manual shows where). OBD-Codes.com says they share power and ground circuits, so inspect both connectors and harnesses for chafing, bare wires, burn spots or melted plastic.
Unplug the connectors and look for corroded, burnt or green terminals. Clean them with electrical contact cleaner, let them dry, apply dielectric grease, then clear the code and see if it returns.
If it comes back and you have a multimeter and a wiring diagram, OBD-Codes.com's next steps are to check the sensor's supply voltage (5 or 12 volts depending on the vehicle), check for 5 volts on the signal circuit, and check the ground with a test light while wiggling the harness.
Don't assume the sensor is the answer. RepairPal warns that just replacing a sensor may not fix underlying issues, such as a wiring fault or a broken tone ring.

Typical fixes

Clean and repair corroded or damaged connector terminals
Repair an open ground or signal wire, or a signal wire shorted to voltage
Apply a PCM software update if a TSB covers your vehicle
Replace the camshaft position sensor (RepairPal's most common repair for this code)
Repair a broken tone ring if inspection finds one
Diagnose and replace the PCM only after the wiring and sensor check out

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The engine won't start or stalls
Testing supply, signal and ground circuits needs a meter and wiring diagram you don't have
The connectors and wiring look fine and the code comes back
Other camshaft or crankshaft position codes are also stored

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Can I drive with P0343?

It's not a good idea to put it off. RepairPal rates P0343 'Urgent' and says the engine may not start, and OBD-Codes.com says the engine can die out or run fine until it's restarted and then not restart.

Is P0343 always a bad camshaft sensor?

No. OBD-Codes.com lists wiring faults first (an open ground or signal wire, or a signal wire shorted to 5 volts) and says a faulty sensor is only occasionally the cause. RepairPal lists sensor replacement as the most common repair but also names wiring, a broken tone ring and PCM failure. Check the connectors and wiring before buying parts.

What's the difference between P0342 and P0343?

Both are camshaft position sensor A circuit codes for bank 1. P0342 means the circuit signal is low, and P0343 means a high-input fault, which OBD-Codes.com ties to an open circuit or a short to voltage.

What's the difference between P0343 and P0348?

Both mean a camshaft position sensor A circuit high fault. P0343 is bank 1 (the side with cylinder 1) and P0348 is bank 2, per OBD-Codes.com's numbering. RepairPal's title for P0343 doesn't mention the bank, so check your vehicle's service information to confirm which sensor it means.

Sources

Last reviewed 2026-10-24. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.