Chevy P1345 Engine Code: Diagnosis & Repair

Receiving a P1345 code on your Chevy or GMC vehicle will read out as “Crankshaft Position-Camshaft Position Correlation”. While this error code can be caused by a faulty camshaft position sensor (CMP) or crankshaft position sensor (CPS), the issue a lot of the time relates to engine timing. On older Chevy engines, specifically the 5.7 Vortec, for which this code is most common, the problem generally stems from the Distributor positioning.

Crankshaft Position to Camshaft Position Correlation

On newer vehicles, the engines adjust the timing themselves. Therefore if you’re experiencing poor timing or a rough running engine, you’re more likely to have a faulty CPS or CMP and get engine code P0340 or P0355. Replacing the bad sensor will usually do the trick if this is the case. On the 5.7 Vortec however, engine timing can require manually adjustment when it gets out of spec, and poor timing is the main cause of the P1345 engine code.

What Causes the P1345 Engine Code?

The crankshaft and camshaft position sensor both work in conjunction with the ECM to control engine timing. When one of these sensors goes bad or fails, inaccurate positioning signals are fed to the ECM. Because the crankshaft and camshaft work cohesively together, an inaccurate signal will cause the two to fall out of sync. This is referred to as engine timing, and when they are out of sync, you have bad timing which causes the engine to run poorly.

While a failed CPS or CMP can cause a P1345 code, it is usually easier diagnosed as you will likely also receive an engine code for whichever sensor has failed. Additionally, you can easily inspect both of these sensors to insure they aren’t gunked with oil or have bad connections.

A P1345 code is most common among Chevy’s 5.7L Vortec engine along with other late-90’s and earlier engines. On these older vehicles, the P1345 is most commonly caused by the distributor.

Symptoms

• Rough idle, stalls out at idle
• Engine runs very poorly
• Engine hard starts or no starts
• Cylinder misfires
• Ticking noise from the engine

Chevy P1345 Causes

• Faulty camshaft position sensor (CMP) (P0340 code)
• Faulty crankshaft position sensor (CPS) (P0355 code)
• Stretched timing chain
• Incorrect distributor positioning or bad distributor
• Bad wire hardness connection (can get burned or become frayed)

How to Fix the Distributor

Distributors are electrical boxes that transfer current to ignition coils so that the ignition coils can allow the spark plugs to fire. The distributor is responsible for making sure the current is delivered to the proper coil in the correct firing order and for the proper amount of time. The distributor has a rotating arm inside of it which spins around and provides the current to the proper ignition coils.

If a distributor fails or the gear inside of it goes bad, the rotating arm will not deliver current to the right coil at the right time. The result is misfires and the engine timing getting all out of whack.

If you have a bad distributor, you will need to replace it. If you just replaced your distributor and you’re still getting the P1345 code, your distributor positioning is likely off. Because of the spinning rotor arm inside, the distributor needs to be properly aligned where the rotor points directly at the first cylinder’s respective coil in the timing sequence.

How-to Adjust Distributor Positioning

The first step is to confirm that you’re timing is off in the first place. To do this, follow these steps:

1. Install a scan tool to the OBD while the ignition is in the OFF position
2. Start the engine and let it get to normal running temps
3. Read the “Cam Retard Offset” with your scan tool
4. The reading will not be accurate under 1k rpms, so give the engine some throttle
5. If the reading falls with +/- 2 degrees of ZERO then your timing is fine (a zero reading is perfect timing, but 2 degrees is an acceptable variance)
6. If your reading is outside of -2 to +2 degrees, then you need to adjust your distributor

When you’re outside the acceptable range, you have to adjust the distributor positioning. To do so, follow these steps:

1. Loose the distributor hold down bolt with engine OFF
2. Make sure your OBD scanner is plugged in to monitor the Cam Retard Offset reading
3. Turn the engine on, let it warm to normal operating temps, and get the rpm’s above 1,000
4. If your reading is negative, turn the distributor counterclockwise
5. If your reading is positive, turn the distributor clockwise
6. Turn distributor as needed until reading is with -2 to 2 degrees