The P0340 Code Meaning, Causes, and Fixes on Your Chevy Silverado

Whoever likes a strutting car when they are returning from a fun trip or going on long drives with their beloved? Well, with the P0340 code, this has been the complaint of many!

The P0340  on a Chevy Silverado denotes an issue with the Camshaft Position Sensor A Circuit (Bank 1 or single sensor). When the powertrain control module (PCM) no longer detects the signal from the camshaft position (CMP) sensor on bank 1, the test fails.

In this article, I will first discuss why this problem actually occurs and then discuss the solution. But if you learn the basics, you will find any way to solve the issue as this problem can be caused by many reasons (most of them being vague). So stay tuned!

What Does P0340 Code Mean On Chevy Silverado?

When the powertrain control module (PCM) no longer detects the signal from the camshaft position (CMP) sensor on bank 1, the test fails.

They read the cam and piston positions so that your spark plug knows when to fire. If this information is not properly read, the performance of your Silverado will suffer.

The Camshaft Position Sensor detects magnetic flux changes between the reluctor wheel’s four narrow and wide tooth slots. For each camshaft revolution, the Camshaft Position Sensor generates a digital ON/OFF DC voltage with varying frequency.

The reluctor wheel interrupts a magnetic field produced by a magnet within the sensor as the camshaft rotates. The internal circuitry of the sensor detects this and generates a signal, which the PCM reads.

The PCM uses this 1X signal in conjunction with the 24X signal from the crankshaft position sensor to determine crankshaft position and stroke. This Camshaft Position sensor diagnostic checks for a loss of the Camshaft Position sensor signal.

The engine will start as long as the Crankshaft Position Sensor 24X signal is present.

Essentially, the sensor is not seeing a signal from the camshaft because the circuit is not complete. It will not set the same code for camshaft sensor error because crankshaft errors have their own set of codes. The problem is almost always a sensor or wiring issue.

Now, let’s look at what the different parts of the code P0340 signify:

• P- Powertrain, the assembly of parts that move your car forward.
• 0 – Standardized code.
• 3 – Ignition or Misfire
• 40 – specific problem. In this case, camshaft Position Sensor A Circuit (Bank 1 or single sensor).

What Happens When the Code P0340 On Chevy Silverado Appears?

A surging or bucking truck is the common scenario when this code appears. Your SES light will display the code P0340 frequently. The Silverado will also suffer from a rough idle and bad misfires.

What Causes Code P0340 On Chevy Silverado?

Since it says “circuit,” any component of the circuit, including the sensor itself, the wiring, or the PCM, could be the cause of the issue. A code P0340 could indicate one or more of the following:

• A grounded, shorted, or broken wire. A nicked wiring caused by the belt is common.
• A grounded, shorted, or broken connector in the circuit.
• A failed camshaft position sensor. The CMP (Camshaft position sensor) circuit is open or is shorted to GND.
• CMP is installed incorrectly (Hall-effect sensor).
• CMP GND is open (Hall-effect sensor).
• CMP circuit voltage short.
• CMP sensor shielding has been damaged.
• A failed PCM.
• A failed crankshaft position sensor.
• SIG RTN is open (VR sensor). A voltage regulator or alternator can be the problem.
• Timing components may be stretched or misaligned.
• ECM software is not updated.

How To Fix The P0340 Code On The Chevy Silverado?

Step 1

Start by examining the sensor’s location and state. It appears that these are mounted on tiny metal tangs. It is possible that perhaps the metal was bent.

If you can test the unit, that might save you some hassles.

Step 2

Check the wiring for continuity and damage. For this, you will have to visually check each wire and connector in the circuit. Verify the camshaft position sensor’s operation by voltage checking.

Replace circuit wiring and/or connectors as necessary. Replace any damaged plugs, wires, caps, and rotors with all brand-new AC Delco products.

Step 3

Check the crankshaft position circuit, and replace the camshaft position sensor as necessary. The camshaft sensor connection may come loose. In that case, tighten the connection.

If the sensor is damaged or broken, replace it. The cam sensor is very simple to replace. It’s a surprisingly easy device to use.

After removing the cap and rotor from the distributor, the cam sensor can be removed with just two more screws and a harness connector.

Step 4

Diagnose the PCM. Look at the ground wire near the “Beefy Nut On A Stud” on the front passenger-side engine head. Keep an eye out for any Ground Cable issues that are loose.

Check the Under-Hood PDC’s (Power Distribution Center) ECM-PCM Fuses next. Remove the cover from the PDC and use the “Scope-On-A-Rope” Power Probe. If these Circuits are functional, you should be able to see a nice, bright light in the probe handle.

FUSE #56 should be checked first (key ON HOT in RUN or START). Next, check the ECM-PCM Battery Fused Circuit’s power by testing FUSE # 12 (HOT AT ALL TIMES). FUSE #4 is then checked for control of the power train relay.

If there is no light, the PCM cannot control the Power Control Relay. This is a very strong indicator of an ECM-PCM unit failure. The PCR Relay should also be tested or replaced.

Find a (5) Volt Reference Signal from the PCM at Different Modules Under the Hood and the Dash. Unplug the MAP Sensor Connector using the Scan Tool’s DMM Voltmeter setting.

Back-probe the GRAY Wire while the Key is Turned, checking the DMM Voltmeter for approximately (5) Volts DC. Next, use his DMM Voltmeter to back-probe the MAF Sensor at the TAN-BLACK Wire for the IAT Voltage, looking for the same (5) Volts DC.

Under the dash at the accelerator pedal, finally search for (5) Volts DC by back-probing the two middle WHITE/BLACK and TAN Wires for the HIGH and LOW Reference Voltages.

Verify that there are (5) Volts DC in each of these locations. Additionally, you must check for battery voltage between 12.5 and 13 VDC. Also check any voltage drops that take place directly at the ECM-PCM.

If you find problems in this step, or a bad PCM is diagnosed, you will have to replace it. Here’s how to do that:

• Install a New ECM-PCM in the Silverado.
• Then connect the OBD2 Port to a J-2534 Unit acting as a PASS-THRU Device via a Laptop Computer.
• This is done to Re-Program the New PCM with the Correct Truck VIN via a TIS2WEB Update.
• Also perform a Security Re-Learn for both Owner Ignition Keys, as well as the necessary CASE Re-Learn.

Step 5

Check the compression and make sure it is correct. You may find the driver-side gauge not holding the pressure in the gauge after shutting it down. There may be a gasket leak on that side.

Check for gasket leaks. How does your coolant level look? A gasket leak could be the reason for the milky stuff or the oil leak.

If you find such symptoms, change the gasket and the engine fluid immediately.

How Much Does It Cost To Fix The Chevy Silverado P0340 Code?

The Camshaft sensor can cost about $70-115. A replacement of the powertrain control module for a Chevrolet Silverado 1500 costs between $510 and $600 on average. This includes both parts and labor.

The diagnosis and fix of code P0340 may cost from $100 to $1,000 at the dealership, depending on the underlying cause of the problem. This includes replacing all the damaged wiring and harness.

Can You Drive Your Chevy Silverado With Code P0340?

You really should not drive with this code. This is an extremely serious diagnostic trouble code. It is critical to diagnose and repair the P0340 error code as soon as possible.

The car may suddenly fail to start while driving. There may also be a lack of power. This makes the vehicle unsafe to operate, and the driver and anyone else on the road is likely to be in danger.

FAQs

How to check the timing chain slack in Chevy Vortec?

Check the timing chain slack with a socket that fits the bolt that holds the harmonic balancer in place (so you can turn the engine over a few degrees at a time).

The distributor cap is then removed. Slowly turn the motor over with a breaker bar, then reverse the direction of rotation – all while keeping a close eye on the rotor.

What type of sensor is the camshaft sensor in a Silverado?

It is a Hall effect sensor, so it should go up and down with RPM.

Why does the Silverado fail to start with a P0340 code?

Lost communication with TCM is more likely the problem with not starting. Could be a problem with connectors, the actual wires, or the TCM itself.

Conclusion

An important thing to keep in mind in the case of the P0340 codes in Chevy is that the Duramax engines really do not work well with aftermarket sensors. This, along with the knowledge you gained from this article, you should now be able to solve your P0340 code.

I hope all these cues help you in recovering your Silverado again. Cheers!