Guide To P0203 OBD Error Code Solutions

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Is your Car’s Check Engine Light illuminating on the dashboard? Do you find sudden decrease in the fuel economy? And is the car engine running rough with increased emissions from the exhaust? This might be the indication of problems with the fuel delivery system of the car which in other words can be an OBD code P0203 error.

OBD Code P0203 error that the PCM has detected a fault in the fuel injector or the wiring and circuit in association. The Powertrain Control Module monitors the injectors and expects it to be in correct voltage range all the time, low or close to zero when activated and high when switched off. If the voltage of the injector and the resistance from the circuit are not in acceptable ranges, the PCM will set the OBD code P0203.

What causes the problem of Cylinder 3 Injector Circuit Malfunction?

• Damaged cylinder 3 fuel injector
• Defective injector power circuits
• Clogged fuel filter screens in the pressure regulator
• Damaged fuel return line
• Improperly installed fuel filters
• Faulty fuel pressure sensor
• Defective fuel pump driver/relay
• Open, short, or corroded electrical wirings and connections

1. Engine Control Module - ECM faults can store and display wrong OBD Code which can result in wrong diagnosis. Thus, replace the damaged components now.
2. Powertrain Control Module - PCM issues directly affects the engine control and transmission control module. Thus, replace faulty components now.
3. Diagnostic Tool - Find wide range of diagnostic tools to detect and correct the OBD code error.
4. Fuel Injection - This system is responsible for supplying fuel with certain pressure, thus assisting the fuel delivery system and engine combustion process. Replace faulty/damaged injectors now!
5. Engine Wiring Harness - Damaged, broken or corroded wiring can cause the fuel delivery system to fail and the components to not work properly. These are easier to check and replace. Purchase new wiring harness and replace the faulty one.
6. Fuel Sender Connector - If the problem in not with the injector, check for the connector and replace or repair as needed. This will ensure steady flow of fuel in the engine.
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Some of the prominent symptoms include:

Common Symptoms

• Vehicle put into failsafe mode by the PCM
• Vehicle running poorly, stalling and not starting
• Check Engine Light illuminated
• Misfiring of car engine
• Lean and rich engine conditions with rough engine idles
• Increased fuel consumptions
• Black smoke emission from tailpipe
• Oil dilution in some cases
• Fouled spark plugs

Following are the most common treatment to the problem related to OBD Code P0203:

• Damaged fuel lines replacement
• Fuel pump replacement
• Fuel pressure sensor replacement
• Fuel injector cylinder 3 replacement
• Damaged wiring and connector replacement
• Fuel pressure regulator replacement

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Following are the diagnostic steps:

• Make use of quality diagnostic tools like OBD-II scanner, DVOM, and automobile stethoscope to treat P0203 error code.
• First step in to inspect for the faulty wiring and connectors that may be damaged, broken or corroded and replace them immediately.
• PCM used other input signals from various engine sensors to develop a fuel delivery strategy. As voltage from the PCM gets increased, the fuel pressure regulator actuator allows pressure from the fuel pump to build and as voltage from the PCM is decreased, fuel pressure gets restricted.
• Retest the system after repairs are completed to ensure that the OBD code doesn’t reappear. If all system wiring, connectors, and components appear to be in normal working order, connect the scanner to the diagnostic connector and record all stored codes and freeze frame data.
• Check for the faults in the fuel pump, and the fuel injection system for any possible leaks and the thus need replacement as required.
• Also check for damaged or clogged fuel filters and replace them if needed.
• Next, check the voltage at the injector itself. Use the scan tool to monitor injector operation. If all of this pass, a noid light will be installed into the wiring of the cylinder 3 injector to check for the proper voltage pulse.
• Check for faults in the Powertrain Control Module and replace or repair as necessary.

Common mistakes when diagnosing P0203 Code

• Clogged or damaged air filter not checked
• Damaged or contaminated spark plug bot replaced
• Faulty fuel pressure sensor not examined
• Not checking for exhaust leaks
• Fuel injector failure not examined
• Powertrain Control Module (PCM) replaced without doing proper diagnosis
• Wrong fuel used in the vehicle