P2503 Diagnostic Trouble Code

P2503 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a P2503 diagnostic trouble code may include:

Fuel pressure too low
Rich or lean exhaust
Diminished fuel efficiency
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected

Possible Causes :

A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
Faulty IMRC actuator relay (if equipped)
Faulty IMRC actuator/sensor

Repair Processes :

Use the DVOM to test resistance and continuity on all system circuits if actuator and sensor resistance levels are in compliance with manufacturer's specifications. Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed.

Process Tips

Diagnostic trouble code P2503 is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before P2503.

Fortunately, P2503 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P2503 Trouble Code For Specific Cars

P2503 Suzuki Sc100 Mirror Driver Left Circuit Open
P2503 Mazda 818 Transmission Transfer Case Contact Plate Ground Return Open Circuit
P2503 Ferrari Ks Invalid Test - Accelerator Pedal Movement
P2503 Rinspeed Advantige Hydraulic Oil Temperature Sensor Circuit Intermittent
P2503 Mercedes S 600 Air Bag Crash Sensor #1 Feed/Return Circuit Failure
P2503 Mercedes-benz W123 Air Suspension LF Air Spring Solenoid Output Circuit Short To Battery
P2503 Lamborghini P140 Solenoid Relay # 1 Circuit Failure