C3803 Engine Trouble Code
What is C3803?
C3803 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: | C3803 |
C3803 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
C3803 Code Structure
Understanding what each digit means in the C3803 chassis trouble code:
| C | 3 | 8 | 0 | 3 |
|---|---|---|---|---|
| Chassis Code | Ignition System Or Misfire | Engine Oil Temperature Sensor Malfunction | Cold Start Injector 1 Malfunction | Exhaust Gas Recirculation Sensor B Circuit High |
How to Fix C3803
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:
C3803 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.
C3803 Description
C3803 engine trouble code is related to Exhaust Gas Recirculation Sensor B Circuit High.
Main Cause
The primary reason for C3803 OBD-II Engine Trouble Code is: Engine Oil Temperature Sensor Malfunction.