C1939 Engine Trouble Code
What is C1939?
C1939 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 Chassis (C) Trouble Code |
| System: | Chassis |
| Code: | C1939 |
C1939 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
C1939 Code Structure
Understanding what each digit means in the C1939 chassis trouble code:
| C | 1 | 9 | 3 | 9 |
|---|---|---|---|---|
| Chassis Code | Fuel And Air Metering | Injector Circuit Malfunction - Cylinders | Injection Pump Fuel Metering Control 'A' High | Reverse Input Circuit |
How to Fix C1939
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:
C1939 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.
C1939 Description
C1939 engine trouble code is related to Reverse Input Circuit.
Main Cause
The primary reason for C1939 OBD-II Engine Trouble Code is: Injector Circuit Malfunction - Cylinders.