2003 Dodge Neon Error Codes

The first code is a thermostat rationality code, here's the book info for that, the other coder are for small and gross leaks in the evap emmisions system, possibly the radiator cap, or a hose leak.
DTC P0128: THERMOSTAT RATIONALITY Monitored & Set Conditions Thermostat Rationality is monitored with ignition on, engine running. The PCM predicts a coolant temperature value that it will compare to the actual coolant temperature. DTC will set if the two coolant temperature values are not within 18 °F (10 °C) of each other an error is detected. This is a two trip fault. Possible Causes à   Good Trip Equal To Zero à   Low Coolant Level à   Other Possible Causes à   Signal Circuit Shorted To Battery Voltage à   Thermostat Operation à   Temperature Sensor Voltage Below 1.0 Volt à   Signal Circuit Open à   Sensor Ground Circuit Open à   Signal Circuit Shorted To Ground à   Signal Circuit Shorted To Sensor Ground à   PCM Low à   PCM High Testing WARNING: When the engine is operating, do not stand in a direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. NOTE: For component location, see COMPONENT LOCATIONS. For connector identification, see CONNECTOR IDENTIFICATION. For circuit identification and wiring diagram, see WIRING DIAGRAMS. In testing procedures Alpha/Numeric character in patientness i.E. (K4) designates circuit. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly. NOTE: If any Engine Coolant Temperature (ECT) sensor, Ambient Air Temperature (AAT) sensor, Camshaft Position (CMP) sensor or Crankshaft Position (CKP) sensor DTCs have set along with P0125, diagnose them first before continuing. See DIAGNOSTIC TROUBLE 1. Ignition on, engine not running. With the DRBIII  scan tool, read DTCs and record the related freeze frame data. Is the Good Trip displayed and equal to zero? If yes, go to next step. If no, see INTERMITTENT CONDITION under SELF-DIAGNOSTICS SYSTEM. 2. Check the coolant system to make sure that the coolant is in good condition and at the proper level. Is the coolant level and condition OK? If yes, go to next step. If no, Inspect the vehicle for a coolant leak and add the necessary amount of coolant. 3. This test works best if performed on a cold engine (cold soak). Ignition on, engine not running. With the DRBIII  scan tool, read the ECT Deg value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature. If engine coolant temperature is above 180 °F (82 °C), allow the engine to cool until 150 °F (65 °C) is reached. Start the engine. During engine warm-up, monitor the ECT degree value. The temperature degree value change should be a smooth transition from start up to normal operating temperature 180 °F (82 °C). Also monitor the actual coolant temperature with a thermometer. As the engine warms up to operating temperature, the actual coolant temperature (thermometer reading) and the ECT Deg in the DRBIII  scan tool sensor should stay relatively close to each other. The proper opening temperature of the thermostat is 192-199 °F (88-93 °C). Did the thermostat open at the proper temperature? If yes, go to next step. If no, replace the thermostat. 4. Turn the ignition on. With the DRBIII  scan tool, read and record the AAT sensor temperature value Using the DRB temperature probe (CH7050), measure the AAT near the AAT sensor. Is the AAT sensor value with 5 °F (-15 °C) of the temperature probe reading? If yes, go to next step. If no, go to step 7. 5. Turn the ignition on. With the DRBIII  scan tool, read and record the ECT sensor temperature value Using the DRBIII  scan tool temperature probe (CH7050), measure the engine coolant CODE DEFINITIONS. Ensure that pinion factor has been programmed correctly into the PCM. WARNING: Never open the cooling system when the engine is hot. The system is under pressure. Extreme burns or scalding may result. Allow the engine to cool before opening the cooling system. NOTE: If a Engine Coolant Temperature (ECT) DTC is set along with this code, diagnose the ECT DTC first. NOTE: The best way to diagnose this DTC is to allow the vehicle to sit overnight outside in order to have a totally cold soaked engine. Inspect the ECT terminals and related PCM terminals. Ensure the terminals are free from corrosion and damage. Extremely cold outside ambient temperatures may have caused this DTC to set. WARNING: Make sure the engine cooling system is cool before removing the pressure cap or any hose. Severe personal injury may result from escaping hot coolant. The cooling system is pressurized when hot temperature. Is the ECT sensor value with 5 °F (-15 °C) of the temperature probe reading? If yes, go to next step. If no, go to step 7. 6. Inspect the temperature sensors for any physical damage. Inspect the engine coolant. Ensure the coolant is at the proper level. Ensure the temperature sensors are properly mounted. Ensure the CMP and CKP sensors are mounted properly. Check the connectors for any signs of damage. Refer to any Technical Service Bulletins (TSBs) that may apply. With the engine running at normal operating temperature, monitor the temperature sensor parameters while wiggling the wire harness. Look for parameter values to change. Visually inspect the related wire harness. Look for any chafed, pierced, pinched, partially broken wires and broken, bent, pushed out, or corroded terminals. Inspect and clean all PCM, engine, and chassis grounds. Were any problems found during the above inspections? If yes, repair as necessary. If no, test complete. 7. Visually inspect both the component and the PCM connectors. Look for damage, partially broken wires and backed out or corroded terminals Turn the ignition off. Disconnect the applicable temperature sensor harness connector. Ignition on, engine not running. Measure the voltage of the signal circuit in the applicable temperature sensor harness connector. Is the voltage above 5.2 volts? If yes, repair the short to battery voltage in the signal circuit. If no, go to next step. 8. Turn the ignition off. Disconnect the applicable temperature sensor harness connector. Ignition on, engine not running. With the DRBIII  scan tool, read the temperature sensor voltage. Is the voltage above 4.6 volts? If yes, go to next step. If no, go to step 12. 9. Turn the ignition off. Disconnect the applicable temperature sensor harness connector. Using a jumper wire, jumper across the temperature sensor harness connector. Ignition on, engine not running. With the DRBIII  scan tool, read the temperature voltage. Is the voltage below 1.0 volt? If yes, replace the applicable temperature sensor. If no, go to next step. 10. Turn the ignition off. Disconnect the applicable temperature sensor harness connector. Disconnect the PCM harness connectors. Measure the resistance of the signal circuit from the temperature sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the open in the signal circuit. WARNING: When the engine is operating, do not stand in a direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis. CAUTION: Do not probe the PCM harness connectors. Probing the PCM 11. Turn the ignition off. Disconnect the applicable temperature sensor harness connector. Disconnect the PCM harness connectors. Measure the resistance of the sensor ground circuit from the AAT sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, replace and program the PCM. See PROGRAMMING. If no, repair the open in the sensor ground circuit. 12. Turn the ignition off. Disconnect the applicable temperature sensor harness connector. Disconnect the PCM harness connectors. Measure the resistance between ground and the signal circuit in the temperature harness connector. Is the resistance below 100 ohms? If yes, repair the short to ground in the signal circuit. If no, go to next step. 13. Turn the ignition off. Disconnect the applicable temperature sensor harness connector. Disconnect the PCM harness connectors. Measure the resistance between the signal circuit and the sensor ground circuit in the temperature sensor harness connector. Is the resistance below 100 ohms? If yes, repair the sensor ground shorted to the signal circuit. If no, If there are no possible causes remaining, replace and program the PCM. See harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis. NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage or terminal push out. Repair as necessary.

P0440= general evap system failure, test this way:Testing 1. If any of the following DTCs are set (DTC P0443, DTC P0452, DTC P0453, DTC P0498 or DTC P0499) diagnose them first before continuing with P0440, see DIAGNOSTIC TROUBLE CODE DEFINITIONS. Ignition on, engine not running. With the DRBIII Â scan tool, read DTCs and record the related freeze frame data. Is the Good Trip Counter displayed and equal to zero? If yes, go to next step. If no, see INTERMITTENT CONDITION under SELF-DIAGNOSTICS SYSTEM. 2. Perform a visual and physical inspection of the entire evaporative emission system. Check for the following conditions; hoses disconnected or left off, holes or cracks, loose seal points, evidence of damaged components, incorrect routing of hoses and tubes, fuel cap left off or bad gasket seal. Were any of the conditions found? If yes, repair as necessary. If no, go to next step. 3. Turn the ignition off. Carefully inspect the EVAP purge solenoid vacuum supply hose for proper routing. Check for a pinched or plugged hose from the throttle body to the purge solenoid. Ensure the vacuum port at the throttle body is free from any blockage. Were any problems found? If yes, repair or replace the vacuum supply, hose/tube as necessary. If no, go to next step. 4. Disconnect the vacuum supply hoses form the EVAP purge solenoid. Using a hand vacuum pump, apply 10 in. Hg to the "CAN" side of the EVAP purge solenoid. Ignition on, engine not running. Observe the vacuum gauge. With the DRBIII Â scan tool, actuate the EVAP purge solenoid. Does the vacuum drop when the solenoid is actuated? If yes, go to next step. If no, replace the EVAP purge solenoid. 5. The fuel level must be below 85 percent, or the Onboard Refueling Vapor Recovery (ORVR) system control valve will seal the tank. Turn the ignition off. Install the Miller Gas Cap Adaptor (8382). Attach the gas cap to the adapter. Connect a hand-held vacuum pump to the gas cap adapter. Note, at 1 in. Hg the switch should close. Using a Miller Manometer (6872A) connected to the service port can aid in properly reading the system vacuum. Slowly apply vacuum while monitoring the NVLD switch state on the DRBIII Â scan tool. Do not exceed 2 in. Hg while performing this step. The NVLD switch reads normally open. When the vacuum is applied and 1 in. Hg is reached the switch state should be in the closed position. Once the vacuum has been released the switch state should return to the open position. Did the NVLD switch operate as described above? If yes, see INTERMITTENT CONDITION under SELF- DIAGNOSTICS SYSTEM. If no, go to next step. 6. To continue testing you will need Miller Tool (8404) Evaporative Emission Leak Detector (EELD). Connect the Red power lead of EELD to the battery positive terminal and the Black ground lead to battery negative terminal. Block the vent hose of the EVAP canister. Connect shop air to the EELD. Set the SMOKE/AIR control switch to AIR. Insert the testers AIR supply tip (clear hose) into the 0.040" orifice on the testers control panel. Press the remote SMOKE/AIR start button. Position the Red flag on the air flow meter so it is aligned with the WARNING: Keep lit cigarettes, sparks, flames, and other ignition sources away from the test area to prevent the ignition of explosive gases. Keep the test area well ventilated. NOTE: The fuel tank should have between 20-80 percent of fuel tank capacity to properly test the EVAP system. Indicator ball. When the calibration is complete, release the remote button. The EELD is now calibrated the flow meter in liters per minute. Install the Service Port Adapter (8404-14) on the vehicles service port. Connect the AIR supply hose from the EELD to the service port. Press the remote button to activate AIR flow. Larger volume fuel tanks, lower fuel levels or if the vehicle is equipped with a Flow Management Valve, this may indicate high flow and will require 4-5 minutes to fill. Compare the flow meter indicator ball reading to the Red flag. ABOVE the Red flag indicates a leak present. BELOW the Red flag indicates a sealed system. Is the indicator ball above the Red flag? If yes, go to next step. If no, go to step 8. 7. A thorough visual inspection of the EVAP system hoses, tubes, and connections may save time in your diagnosis. Look for any physical damage or signs of wetness at connections. The strong smell of fuel vapors may aid diagnosis also. To continue testing, you will need Miller Tool (8404) Evaporative Emissions Leak Detector (EELD). Remove the AIR supply hose from the service port. Connect the SMOKE supply tip (Black hose) to the service port. Set the SMOKE/AIR control switch to SMOKE. The flow meter indicator ball will not move at this point. Press the remote SMOKE/AIR start button. Ensure that smoke has filled the EVAP system by continuing to press the remote SMOKE/AIR start button, remove the vehicle fuel cap, and wait for the smoke to exit. Once smoke is indicated reinstall the fuel cap. For optimal performance, introduce smoke into the system for an additional 60 seconds, continue introducing smoke at 15 second intervals, as necessary. While still holding the remote SMOKE/AIR start button, use the White Light (8404 CLL) to follow the EVAP system path, and look for the source of the leak indicated by exiting smoke. If a leak is concealed from view (i.E, top of fuel tank), release the remote SMOKE/AIR start button, and use the Ultraviolet (UV) Black Light (8404 UVL) and the Yellow Goggles (8404-20) to look for residual traces of dye that are left behind by the smoke. The exiting smoke deposits a residual fluid that is either bright Green or bright Yellow in color when viewed with a UV light. Carefully inspect the vent side of the EVAP canister. Due to the filtering system in the canister the smoke or dye may or may not be visual. Introducing smoke into the filtered side of the canister may assist in locating the leak. Was a leak found? If yes, repair or replace the leaking component as necessary. If no, before continuing disconnect the PCM harness connector and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace and program the PCM. See PROGRAMMING. 8. Turn the ignition off. Disconnect the NVLD assembly electrical harness connector. Check connectors, clean/repair as necessary. Using a jumper wire, jumper across the (K107) NVLD switch sense circuit and the (Z1) ground circuit in the NVLD electrical harness connector. Monitor the NVLD switch state on the DRBIII Â scan tool. Does the switch change from OPEN to CLOSED. If yes, replace the NVLD assembly. If no, go to next step. 9. Turn the ignition off. Disconnect the NVLD assembly electrical harness connector. Measure the resistance between the (Z1) ground circuit and ground. Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the open in the (Z1) ground circuit. 10. Turn the ignition off. Disconnect the NVLD assembly electrical harness connector. Disconnect the PCM harness connectors. Measure the resistance of the (K107) NVLD switch signal circuit from the NVLD assembly electrical harness connector to the appropriate terminal of the Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, before continuing disconnect the CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis. PCM harness connector and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace and program the PCM. See PROGRAMMING. If no, repair the open in the (K107) NVLD switch signal circuit.
DO NOT Test without the Miller tool! Damage to the wiring harness can occur.