C1503 Engine Trouble Code
What is C1503?
C1503 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: | C1503 |
C1503 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
C1503 Code Structure
Understanding what each digit means in the C1503 chassis trouble code:
| C | 1 | 5 | 0 | 3 |
|---|---|---|---|---|
| Chassis Code | Fuel And Air Metering | Fuel Composition Sensor Circuit Malfunction | Cold Start Injector 1 Malfunction | Exhaust Gas Recirculation Sensor B Circuit High |
How to Fix C1503
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:
VSS concerns may stem from noisy input signals caused by RFI/EMI from ignition wires, charging circuits, or aftermarket equipment. Verify VSS reads 0 mph when transmission is in Park.
Technical Notes:
C1503 DTC specifically relates to camshaft timing. When cam timing is over-retarded, the check-engine light illuminates and this code sets. Verify VCT solenoid operation and check for contamination.
C1503 Description
C1503 engine trouble code is related to Exhaust Gas Recirculation Sensor B Circuit High.
Main Cause
The primary reason for C1503 OBD-II Engine Trouble Code is: Fuel Composition Sensor Circuit Malfunction.