P252C Low engine oil quality sensor circuit

P252C Low engine oil quality sensor circuit

OBD-II DTC Datasheet

Low signal level in the engine oil quality sensor circuit

What does this mean?

This is a Generic Powertrain Diagnostic Trouble Code (DTC) applicable to many OBD-II vehicles (1996 and newer). This may include, but is not limited to, vehicles from General Motors, VW, Ford, BMW, Mercedes, etc. Despite the general nature, the exact repair steps may vary depending on the model year, make, model, and transmission configuration.

OBD-II DTC P252C and corresponding codes P252A, P252B, P252D and P252E are associated with the engine oil quality sensor circuit.

The oil quality sensor circuit is designed to send a signal to the engine control module (ECM) indicating the overall condition of the engine oil. This circuit monitors the quality, temperature and level of the engine oil. The engine oil quality sensor is one of the main components in this circuit and is located on the engine oil pan. The exact location and operation of the sensor varies from vehicle to vehicle, but the purpose of this circuit is the same. Configurations will vary with instruments built in to monitor engine oil and display status on the dashboard to alert the driver. Some vehicles may be equipped with sensors or indicators for oil temperature, oil level and / or oil pressure.

When the ECM detects that the voltage or resistance in the oil quality sensor circuit is too low, below the normal range threshold, a P252C code will set and the check engine light, engine service light, or both may illuminate. In some situations, the ECM can shut down the engine and prevent it from restarting until the problem is corrected and the code is cleared.

Oil quality sensor:

What is the severity of this DTC?

This code is serious and requires immediate attention as insufficient lubrication or oil pressure can very quickly cause permanent damage to internal engine components.

What are some of the symptoms of the code?

Symptoms of a P252C trouble code may include:

• Engine cannot crank
• Low oil pressure gauge reading
• Service engine light will be on soon
• Check engine light is on
• Oil check message on instrument cluster

What are some of the common causes for the code?

Reasons for this P252C code may include:

• Defective engine oil quality sensor
• Low engine oil level
• Poor quality oil
• Faulty or damaged wiring
• Corroded, damaged or loose connector
• Defective ECM

What are some steps to troubleshoot the P252C?

The first step in troubleshooting any problem is to review the vehicle-specific Technical Service Bulletins (TSBs) by year, model, and powerplant. In some cases, this can save you a lot of time in the long run by pointing you in the right direction.

The second step is to check the condition of the engine oil and make sure it is maintained to the proper level. Then locate all components associated with the engine oil quality sensor circuit and look for obvious physical damage. Depending on the specific vehicle, this circuit may include several components, including an oil quality sensor, switches, malfunction indicators, an oil pressure gauge, and an engine control unit. Perform a thorough visual inspection to check the associated wiring for obvious defects such as scratches, abrasions, exposed wires, or burn marks. Next, check the connectors and connections for security, corrosion and damage to the contacts. This process should include all electrical connectors and connections to all components, including the ECM. Consult the vehicle specific data sheet to check the oil quality sensor circuit configuration and confirm each component included in the circuit, which may include a fuse or fusible link.

Advanced steps

The additional steps become very vehicle specific and require appropriate advanced equipment to be performed accurately. These procedures require a digital multimeter and vehicle-specific technical reference documents.

Voltage test

The reference voltage and allowable ranges may vary depending on the specific vehicle and circuit configuration. Specific technical data will include troubleshooting tables and appropriate sequence of steps to help you make an accurate diagnosis.

If this process detects that a power source or ground is missing, a continuity test may be required to verify the integrity of wiring, connectors, and other components. Continuity tests should always be done with power disconnected from the circuit and normal readings for wiring and connections should be 0 ohms of resistance. Resistance or no continuity indicates a wiring fault that is open, shorted, or corroded and needs to be repaired or replaced.

What are the standard ways to fix this code?

• Replacing the engine oil quality sensor
• Cleaning connectors from corrosion
• Repair or replace faulty wiring
• Oil and filter change
• Repair or replacement of faulty grounding tapes
• Flashing or replacing ECM

General error

• The ECM sets this code after replacing the engine oil quality sensor with faulty wiring.

Hopefully the information in this article has helped point you in the right direction to troubleshoot your oil quality sensor circuit DTC issue. This article is for informational purposes only and specific technical data and service bulletins for your vehicle should always take priority.

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