What is P0173 : Engine Error Code Causes Explained
The P0173 engine trouble code indicates bank 2’s rich fuel system. This blog describes its prevalent causes, symptoms, and practical troubleshooting ways to help diagnose and fix it.
How to Identify a DTCs Number
The P0173 Engine Error Code indicates that the fuel trim system is running too rich in bank 2, affecting the air-fuel mixture and engine efficiency.
Understand, these trouble codes (DTCs) are 5 characters: 1 letter, 4 numbers. P-Powertrain indicates the fault code’s location. Generic or manufacturer-specific codes are indicated by the first digit. The second digit denotes the subsystem (7=transmission). The last two numbers describe the issue.
An OBD-II scanner linked to the vehicle’s diagnostic port under the dashboard detects the P0173 engine trouble code. The scanner reads engine control module error codes and shows DTC numbers like P0173 when the check engine light comes on.
CAUSES: P0173 Engine Code
- Air/FueI Imbalance:
A faulty or dirty Mass Air Flow (MAF) sensor can provide incorrect airflow readings to the ECM, leading to improper fuel adjustments. - Sensor Malfunctions:
A faulty fuel pressure sensor can provide inaccurate pressure readings to the ECM, leading to improper fuel delivery. - Fuel Delivery Issues:
A weak or failing fuel pump may not be able to deliver enough fuel pressure, leading to a lean condition. - Other Potential Causes:
Damaged wiring or poor connections in the fuel system or sensor circuits can interfere with proper operation.
Risk Level of P0173 Error Code:
The P0173 engine trouble code is Medium Risk. It may not cause engine failure, but it should be treated immediately to ensure vehicle safety. Inspection and repair should be done promptly to avoid issues.
Common Car Brands Affected by P0173 Code: 
The P0173 engine error code is commonly found in the following list.
- BMW
- Mercedes-Benz
Video: P0173 Engine Error code
FAQ’s
What is the P0173 Engine Error Code?
The P0173 Engine Error Code indicates that the fuel trim system is running too rich in bank 2, affecting the air-fuel mixture and engine efficiency.
What causes the P0173 Engine Error Code?
The P0173 Engine Error Code is commonly caused by an Air/fuel imbalance, Sensor Malfunctions, Fuel Delivery Issues, Other Potential Causes or problems with the mass airflow sensor.
What’s the risk level of P0173 Engine Error Code?
The risk level of the P0173 Engine Error Code is Medium, as it may lead to rough idling, reduced fuel efficiency, and minor performance issues.
Which vehicles are affected by the P0173 Engine Error Code?
The P0173 Engine Error Code is seen in vehicles with advanced fuel management systems, including certain BMW, Mercedes-Benz models.