What this code means
P0340 often means the PCM may not be receiving the expected camshaft position signal for Bank 1 Sensor 1.
What the vehicle may do
- The MIL may illuminate.
- The engine may have a delayed start while the PCM establishes position sync.
- The fault may be active, pending, or intermittent.
Possible fault areas
- Possible camshaft position sensor signal circuit issue.
- Possible 5-volt supply or sensor ground issue.
- Possible connector, terminal, or harness problem.
- Possible tone wheel, cam phaser, valvetrain, timing, or oiling-related issue.
Diagnostic path
Opening context for P0340
On this Ram 1500 with the 3.6L Pentastar, P0340 is a camshaft position sensor circuit fault for Bank 1 Sensor 1. In plain terms, the PCM may be losing the cam signal it expects to see while it still has crankshaft position information. The truck may turn the MIL on, and it can sometimes have a delayed start while the PCM sorts out engine position from the remaining inputs. Broadly, this can be a sensor signal issue, a 5-volt or ground problem, connector or terminal trouble, a tone wheel or cam timing issue, or an oil pressure and cam phaser control problem. Treat it like a signal-integrity diagnosis first, then move into oiling and mechanical checks only when the path takes you there.
Monitor gate and code logic
The monitor is allowed to run when battery voltage is above approximately 11.0 volts, with the engine cranking or running. The code can set during cranking after at least 2.5 seconds with a crankshaft position signal present but no camshaft position signal. With the engine running, it can also set if the camshaft position signal is lost for at least 0.4 seconds while the crank signal is still present. So before chasing parts, try to reproduce the captured operating conditions and confirm whether this is active, pending, or intermittent.
Start with oil condition and active-code status
Start with the ignition off and check engine oil level and condition. Look for low oil, dirty or aerated oil, deteriorated oil, incorrect viscosity, oil pressure out of specification, or the wrong oil filter. If anything is wrong there, correct it first. If the oil was low, top it off to the proper specification, start the engine, idle it for 2 - 3 minutes, shut it off, turn the ignition on, clear the code, and drive it to verify. If P0340 comes back, continue with the diagnostic path. Next, turn the ignition on, read and record the codes, and copy the captured data. Start the engine and let it idle, or crank it if it will not start. Try to operate the vehicle under conditions similar to the captured data, then read codes again. If P0340 is active or pending, keep going. If it is not active, move to the intermittent wiring and sensor inspection later in the process. Before getting deep into this circuit, check the other codes that were recorded. If any 5-volt reference, oil pump, or oil pressure related codes are active or pending, diagnose those first. If not, check whether there are related cam sensor faults present at the same time. If related cam sensor faults are present, start with the shared 5-volt and ground checks. If they are not present, go straight to the Bank 1 Sensor 1 signal circuit checks.
Shared 5-volt, ground, and sensor-swap checks
For the 5-volt supply check, turn the ignition off, disconnect the cam sensor connector at the component, and leave the ECU connector connected. Turn the ignition on, set the meter to DC volts, put the negative lead on a known good ground, and measure the 5-volt supply at the component harness connector. Because this code is tied to an intermittent cam signal loss, wiggle the harness and connectors while watching the meter. Normal operating voltage should be between 4.8 and 5.2 volts. If the supply is not correct, repair the 5-volt supply circuit for an open or short, then verify the repair. If the 5-volt supply is correct, isolate the K900 sensor ground circuit and check it for an open or high resistance. With the ignition off, disconnect the ECU and component connectors for that circuit, measure the meter lead resistance first, then measure the circuit resistance between the component connector and the GPEC adaptor. Do not probe the PCM harness terminals directly; use Adapter, GPEC Diagnostic 10436 when access at the PCM connector is needed. The resistance needs to be below 3.0 Ohms. Keep in mind the GPEC Diagnostic Adaptor can add up to 1.5 Ohms of resistance to the circuit. If resistance is too high, repair the open or high resistance and verify the repair. If supply and ground are good, swap CMP Sensor 1 with the CMP sensor on the opposite bank. Inspect the camshaft magnetic tone wheel for damage while you are there. Reconnect the PCM and cam sensor connectors, clear the codes, then idle or crank the engine and run it under conditions similar to the captured data. If the cam sensor fault moves to the opposite bank, replace the faulty camshaft position sensor, perform the Cam/Crank Relearn, and verify the repair. If it does not move, continue into the oil pressure and mechanical side of the diagnosis.
Bank 1 Sensor 1 signal circuit checks
If the path goes directly to the Bank 1 Sensor 1 signal circuit, start with the CMP 1/1 K44 position signal circuit short-to-voltage check. Turn the ignition off, disconnect the component connector, follow the circuit path, turn the ignition on, and measure voltage at the component harness connector. On a 5.0 volt signal or reference circuit, voltage should be between approximately 4.8 and 5.2 volts. If the signal circuit is above 5.2 volts, continue by isolating it and checking for a short to another circuit at the PCM harness connector. For that isolation check, turn the ignition off, disconnect the ECU and every component connector on the circuit, and leave the in-line connectors connected. Check for continuity between the K44 signal circuit and every other circuit at the ECU connector. Use the GPEC adaptor if a PCM terminal must be accessed. If continuity is found to another circuit, repair that short and verify the repair. If no continuity is found, move to connector and PCM-side checks later in the process. If the short-to-voltage check was not above 5.2 volts, check the K44 signal circuit for a short to ground. With the ECU and component connectors disconnected, put the negative meter lead on a known good ground and check continuity between the signal circuit and ground. If continuity is present, repair the short to ground and verify the repair. If not, check for a short between the K44 signal circuit and the K900 sensor ground circuit. If those two circuits have continuity, repair the short and verify. If the signal circuit is not shorted, isolate it and check for an open or high resistance. Measure lead resistance first, then measure resistance from the component connector to the GPEC adaptor. The signal circuit resistance needs to be below 3.0 Ohms. If it is not, repair the open or high resistance and verify the repair.
Oil pressure, cam control, and mechanical checks
Once the electrical checks lead you into the oiling and mechanical side, get the engine to operating temperature and check oil pressure at idle and while driving under the captured conditions. Monitor oil pressure on the scan tool. If you check it manually, shut the engine off, remove the oil filter cap, install Adapter, Late Version 3.6L Oil Pressure Test 2021500090 to the oil filter cap, and install an oil pressure gauge to the adaptor. If that adaptor is not available, monitor oil pressure with the scan tool. The reading needs to be stable and above 16.0 psi. If oil pressure goes below 16.0 psi or oscillates excessively, it can delay cam phaser movement enough to set a slow response or intermittent cam sensor fault. Repair the oiling or mechanical condition, such as drain-back, sludge, oil pump, pick-up tube, or seal issues, then verify the repair. Next, check oil pressure at the cylinder head. Remove the front VVL solenoid, install Kit, VVL Adapters 2027300090 in place of the solenoid, start the engine, let it idle, and monitor oil pressure on the scan tool while operating the vehicle. That reading needs to be stable and above 14.0 psi. If it is not, remove the cylinder head cover and inspect for missing or damaged oil galley plugs or screws near the front of the cylinder head. Verify the plugs are torqued properly. If the plugs are properly torqued and do not appear to be leaking, replace the cylinder head, perform the Cam/Crank Relearn, and verify the repair. Then check the Camshaft 1/2 oil control valve. With the ignition off, remove the VVT exhaust solenoid 1/2, inspect the spring-loaded spool valve, and push and release it with a small punch. It should be flush and move freely without dragging or sticking. If it does not, replace the Camshaft 1/2 oil control valve, perform the Cam/Crank Relearn, and verify the repair. After that, swap CMP Sensor 1 with the sensor on the opposite bank again, clear the codes, and see whether the fault follows the sensor as an active code. If it follows, replace the faulty camshaft position sensor, perform the Cam/Crank Relearn, and verify the repair. If the sensor does not carry the fault to the other bank, remove the cylinder head cover and inspect the camshaft sensor tone wheel for looseness or damage. Use Check Tool, Tone Wheel Right 2027902090, to check tone wheel alignment. If the tone wheel has a problem, replace the camshaft assembly, perform the Cam/Crank Relearn, and verify. Continue by inspecting the cylinder head for missing or improperly torqued oil galley plugs, then inspect the timing chain links, chain pins, and tensioners. If a problem is found, make the appropriate repair, perform the Cam/Crank Relearn, and verify. Finally in this mechanical section, check that the cam phaser has returned to lock pin. Put a wrench on the flat of the camshaft behind the phaser and try to move the camshaft back and forth. At that decision point, if there is movement between the camshaft and cam phaser, replace the cam phaser, perform the Cam/Crank Relearn, and continue to repair verification. If there is no movement, replace the cam phaser and camshaft, perform the Cam/Crank Relearn, and continue to repair verification.
Verify before condemning higher-cost parts
Keep verification separate from testing. Clear the codes with the scan tool and test drive the vehicle under the captured conditions. If P0340 does not return, the repair is complete, and you still confirm the code stays gone. If it does return, move into connection checks before condemning the PCM. Check any applicable bulletins, then disconnect the PCM connectors, related in-line connectors if equipped, and related component connectors. Inspect the harness and component connectors, male and female terminals, connector locks, corrosion, water intrusion, weather seals, bent terminals, overheated terminals, pushed-back terminals, spread terminals, and terminal tension. Repair anything found, reconnect everything fully, make sure the locks are engaged, clear codes, and operate the vehicle under the monitored and set conditions. If the code does not return, the wiring or poor connection repair fixed it. If the code still returns after those checks, replace the PCM and retest. Clear the codes, start the engine, let it idle, and read codes again. If the cam sensor fault returns even after PCM replacement, the next supported repair is the cylinder head assembly, timing chain, and tensioners, followed by Cam/Crank Relearn and repair verification. If the code does not return after PCM replacement, the PCM repaired the fault, and you still verify the repair.
Parallel oiling and connection path
There is also a later path that repeats the same oiling and connection logic. In that path, first bring the engine to operating temperature and confirm oil pressure is stable and above 16.0 psi at idle and during a drive under the captured conditions. If it is not, repair the engine oiling or mechanical condition and verify. Then check cylinder head oil pressure through the front VVL solenoid location with Kit, VVL Adapters 2027300090 installed. The reading needs to be stable and above 14.0 psi. If it is low or unstable, inspect the cylinder head oil galley plugs and screws near the front of the head, verify torque, and repair as needed. If the plugs are properly torqued and not leaking, replace the cylinder head, perform the Cam/Crank Relearn, and verify. Next, inspect the cylinder head oil galley area, timing chain links, chain pins, and tensioners. Repair any issues found and perform the Cam/Crank Relearn. If no issue is found, repeat the PCM and component connector inspection: locks, corrosion, water intrusion, seals, bent or pushed-back terminals, spread terminals, overheating, and terminal tension. Repair any connection problem, clear codes, and run the vehicle under the monitored and set conditions. If the fault still returns after that, replace the PCM and retest. If the cam sensor fault returns after PCM replacement, replace the cylinder head assembly, timing chain, and tensioners, then perform the Cam/Crank Relearn and verify. If it does not return, the PCM repaired the fault.
Intermittent-code path and repair history
If P0340 is not active, treat it like an intermittent. Turn the ignition off, disconnect the PCM and cam sensor connectors, and inspect for harness chafing, rub-through, spread terminals, pushed-out terminals, bent terminals, water in connector cavities, and corrosion. Also inspect the cam sensor mounting area for debris, damage, or a loose sensor. Remove the sensor and inspect the sensor end for damage or debris. Rotate the engine and, if possible, inspect the tone wheel for damage. Reinstall the cam sensor correctly and torque it to specification. If you find a problem, make the appropriate repair and verify. If nothing obvious is found, check the vehicle repair history for prior cam sensor faults. If the current fault is on the same engine bank as a previous visit, pick back up at the signal circuit open or high-resistance check instead of guessing. If the current fault is on the opposite bank, replace the cam sensor, perform the Cam/Crank Relearn, and verify. If there is no useful history, swap the cam sensor with the opposite bank, clear the codes, and verify the code does not return. The practical takeaway: do not jump straight to a sensor or PCM on P0340. Confirm the code status, check the shared feed and ground, prove the signal circuit, and only then move into oil pressure, tone wheel, cam phaser, and timing-related checks. For more diagnostic training, visit stepdiagnostics.com.
Final check
A clean P0340 diagnosis proves the electrical signal path first, then follows the procedure into oil pressure and mechanical checks when needed.
For more guided automotive diagnostics, visit STEP Diagnostics.
