C1904 Engine Trouble Code
What is C1904?
C1904 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: | C1904 |
C1904 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
C1904 Code Structure
Understanding what each digit means in the C1904 chassis trouble code:
| C | 1 | 9 | 0 | 4 |
|---|---|---|---|---|
| Chassis Code | Fuel And Air Metering | Injector Circuit Malfunction - Cylinders | Cold Start Injector 1 Malfunction | Timing Reference High Resolution Signal A Too Many Pulses |
How to Fix C1904
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:
Excessive air inflow may result from vacuum leaks, dirty sensors, or EGR valves not closing properly. Insufficient fuel can stem from dirty injectors, clogged filters, weak fuel pump, or leaking pressure regulator.
Technical Notes:
C1904 DTCs can be triggered by upstream issues. For example, a dirty MAF sensor may cause incorrect fuel-trim adjustments, leading oxygen sensors to report mixture problems. Address root causes first.
C1904 Description
C1904 engine trouble code is related to Timing Reference High Resolution Signal A Too Many Pulses.
Main Cause
The primary reason for C1904 OBD-II Engine Trouble Code is: Injector Circuit Malfunction - Cylinders.