What the P0374 code means
The Powertrain Control Module (PCM) has discovered a problem in the high-resolution timing reference signal.
What causes the P0374 code?
There may be one or more causes for the P0374 code:
A defective camshaft, crankshaft, and distributor position sensors
Mechanical distributor failure, which occurs often in rear-wheel drive vehicles with high-mileage
Damaged, corroded, or faulty wiring and electrical connectors
PCM failure is possible but this very rarely occurs
What are the symptoms of the P0374 code?
Some symptoms are detectable while others are not. For instance, you might experience engine misfire and spark knock while you are accelerating. You may also experience lower fuel mileage. Malfunction lamp illumination may require several failure cycles, depending on what model you have.
How does a mechanic diagnose the P0374 code?
A good starting point for performing a successful diagnosis of the crankshaft position sensor is to check for an engine RPM signal while the engine is running or cranked. This can be done using a scanner or simply by observing your vehicle’s tachometer as the engine is running or being cranked. If you do not see an RPM signal, then inspect the crankshaft position sensor, crankshaft gear, and sensor connector for damage. You will want to repair as soon as possible. If you do not see any signs of damage, you will want to test the CPS system for a reference voltage signal. If you cannot find a pattern, then test the resistance of the CPS sensor and compare those values with the manufacturer’s specifications. If the CPS sensor seems to be working well, then test the system circuitry for the proper resistance and voltage. Always be sure to repair open or shorted wiring as you go. But remember that several specialty tools will be required to diagnose this code successfully. These may include a digital volt/ohmmeter, a scanner, and possibly an oscilloscope.
Common mistakes when diagnosing the P0374 code
Some mistakes include:
Unnecessary replacement of camshaft, crankshaft, and distributor sensors.
Crank and cam reluctor rings also need to be checked any time you are replacing sensors.
When replacing crankshaft or camshaft sensors, you should do these as a set. You might also want to use of OEM sensors as well.
How serious is the P0374 code?
The P0374 code is very serious and should be repaired as soon as possible. Luckily, to repair this issue is not as difficult as some others. But you will want to make sure that as soon as you see this code, you either begin addressing your issue yourself or take your vehicle into a professional technician.
What repairs can fix the P0374 code?
If your optical sensor circuit is damaged, you will want to repair this immediately. You will do this by removing your optical sensor. In rare cases, you will need to replace your PCM or ECM.
Additional comments for consideration regarding the P0374 code
The optical sensor in your vehicle provides a high-resolution signal to the Powertrain Control Module (PCM) by counting pulses on the sensor disk, which is located in your vehicle’s injection pump. One of the most important by the PCM for fuel control and timing, the optical sensor monitors the number of high-resolution pulses which have gone undetected. While you might be able to perform the maintenance by yourself, you will need to be patient and do the proper research in advance. But remember that it is always important to have the right diagnostic tools so that you know just what problems you are searching for and if you have located the correct problem or not. Do not hesitate to consult a professional, even if it is only to ask questions about doing the work yourself. Also, remember to test drive the vehicle and note if the code appears again.
Need help with a P0374 code?
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