B1939 Engine Trouble Code
What is B1939?
B1939 indicates potential catalytic converter failure. If completely failed, your vehicle may not run properly and fuel economy will suffer significantly. Average replacement cost is $2,000–$2,140. This repair requires professional service and should not be delayed.
Code Information
| Code Type: | OBD-II Body (B) Trouble Code |
| System: | Body |
| Code: | B1939 |
B1939 Symptoms
Check Engine Light
Illuminated dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration
Starting Problems
Difficulty starting the engine
B1939 Code Structure
Understanding what each digit means in the B1939 body trouble code:
| B | 1 | 9 | 3 | 9 |
|---|---|---|---|---|
| Body Code | Fuel And Air Metering | Injector Circuit Malfunction - Cylinders | Injection Pump Fuel Metering Control 'A' High | Reverse Input Circuit |
How to Fix B1939
Diagnostic Steps:
The catalytic converter has oxygen sensors before and after it. When warm and in closed-loop mode, the upstream O2 sensor reading should fluctuate, while downstream should remain steady.
Repair Solution:
Regular maintenance of indicator and headlight bulbs ensures proper function. Maintain paint condition to prevent rust. Modern products make these maintenance tasks straightforward and accessible.
Technical Notes:
B1939 DTC indicating a sensor fault does not always mean the sensor itself is bad. The issue may stem from the systems being monitored or even the sensor wiring. Proper diagnosis is essential.
B1939 Description
B1939 engine trouble code is related to Reverse Input Circuit.
Main Cause
The primary reason for B1939 OBD-II Engine Trouble Code is: Injector Circuit Malfunction - Cylinders.