Fix P0000: Mechanic’s solutions that WORKED

The P0000: No Diagnostic Trouble Codes Reported suggests that no specific diagnostic trouble codes were reported by the vehicle’s onboard diagnostic system. This is often more indicative of an issue with the diagnostic equipment or process rather than the vehicle itself.

P0000 quick overview

Meaning	P0000: No Diagnostic Trouble Codes Reported
Is it serious?	This code typically indicates that no specific faults were detected by the diagnostic system, so it is usually not serious in terms of vehicle functionality.
Possible causes	– Diagnostic tool malfunction or compatibility issue – Software glitches in the scanning equipment – Previous error codes cleared but not reset in the system – Interruption or error during the scanning process
How to diagnose?	Check Diagnostic Tool: Verify the functionality and compatibility of the diagnostic scanner. Re-scan Vehicle: Conduct a second scan to ensure no codes were missed. Inspect Vehicle’s OBD System: Check the vehicle’s onboard diagnostic system for proper operation. Consult Technical Bulletins: Look for any manufacturer technical service bulletins that may provide insight. Seek Professional Help: If uncertainty persists, consider a professional diagnostic service for a thorough examination.

How to fix P0000 – learn from mechanics

I looked into P0000 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Ford

Vehicle Information: 1998 Ford Taurus SE 3.0L

Issue + Repair History:

• Experienced stalling and cutting out, reported to happen six times in one morning, especially during turning or going uphill.
• Occurred after a rainy night.
• No issues found during test drives with fuel pressure gauge and soaking/wiggling ignition wires, PCM, and related connectors.
• All sensor readings appeared normal on a Snap-on scanner.
• No documentation of this issue in the fleet database.
• KOEO (Key On Engine Off) and KOER (Key On Engine Running) codes: P0000 (no codes).
• Fuel pressure consistently between 30-35 psi.

Suggestions to Fix Issue:

• Check both MAF (Mass Air Flow) and BARO (Barometric Pressure) sensors; MAF should read 1.25V – 1.30V at cold start.
• Inspect the damper pulley for separation.
• Consider checking the wiring of the spark plugs and updating PCM calibration using a dealer tool.
• Examine EGR valve function and any solenoids or devices controlling it for potential sticking issues.
• Investigate the possibility of TPS (Throttle Position Sensor) being affected by moisture or having a fallout situation.
• Check and clean the air flow meter if necessary.

Final Fix:

• The customer had not returned for this issue, suggesting it might be a rare occurrence.
• No further information was provided on a definitive fix.

Case #2: Acura

Vehicle Information: 1999 Acura TL 3.2L

Issue + Repair History:

• MIL (Malfunction Indicator Lamp) light came on at 15,000 miles.
• The car runs well despite the MIL light being on.
• The only code reading on the scanner was P0000, indicating no known issues.
• The light was reset using a scanner, and no problems were noted.

Other OBD2 Codes + Test Results:

• P0000 – No code known with this number.

Suggestions to Fix Issue:

• Some advised taking the car to the dealer for a check-up.
• Others suggested that there might be nothing wrong and recommended resetting the light.

Final Fix:

• The MIL light was reset, and the car has been functioning well since.
• The technician will repost if the issue recurs.

Case #3: Land Rover

Vehicle Information: 2003 Land Rover Range Rover HSE 4.4L

Issue + Repair History:

• The vehicle had temperature gauge issues and transmission not shifting.
• It showed CAN bus communication faults in modules like the engine, ABS, air ride, transfer case, steering angle sensor, and instrument cluster.
• All these modules communicated with the scan tool but reported CAN bus fault codes.
• Unplugging modules one at a time did not resolve the issue, and the problem reoccurred after a few ignition cycles.
• The instrument cluster’s fluctuation was the first indication of the problem.

Suggestions to Fix Issue:

• Check the thermostat and water pump as a starting point.
• Review technical bulletins for issues related to radiator clogging causing transmission temperature to rise and trigger limp home mode.
• Measure resistance on the CAN bus with the battery disconnected, looking for 60 ohms to confirm the loop is complete.
• Check high side and low side voltages to ground on the CAN bus.
• Inspect for cooling system issues, particularly leaks from the valley area, water pump failures, hose leaks, and thermostat failure.
• Investigate potential physical damage to the electrical wiring, particularly near the battery holder.

Final Fix:

• The issue was traced back to water damage from a leak at the cowl, affecting the transfer case control unit.
• Initially, the wrong component (transfer case servo motor) was unplugged by accident.
• Replacing the control unit resolved the issue, although there was an indication of further work needed due to a coolant smell, suggesting possible cooling system issues.

Case #4: Saturn

Vehicle Information: 2000 Saturn LS2 3.0L

Issue + Repair History:

• Initially reported poor running and hard shifting; engine light was on but turned off later.
• Only code found was P0000, indicating lost communication or undefined code.
• Discovered a loose battery terminal during initial checks.
• After three days, the car showed problems again, but this time with the service wrench light on instead of the check engine light.
• Issues with the wiring harness suspected, along with possible problems between the ECM (Engine Control Module) and BCM (Body Control Module).
• The Modis scanner used had a glitch in software, causing confusion with the P0000 code.
• Throttle body checked and cleaned, which temporarily resolved the issue.

Other OBD2 Codes + Test Results:

• P0000 – Lost communication or undefined Code.
• TPS (Throttle Position Sensor) voltage and ECT (Engine Coolant Temperature) voltage normal.

Suggestions to Fix Issue:

• Pull wrench light DTC (Diagnostic Trouble Code) from BCM; potential issues with BCM or ECM.
• Check for MAF (Mass Air Flow) sensor problems or transmission solenoids issues.
• Look for vacuum leaks from the intake runner hose and check for oil leaking into the throttle body.
• If TCM (Transmission Control Module) shows P1811, consider replacing the pressure control solenoid and updating the TCM.

Final Fix:

• The issue was temporarily resolved by cleaning the throttle body.
• However, there is a belief that there might be an underlying issue with the wiring harness that could cause future problems.
• No further updates provided if the Saturn returned for the same issue.

Case #5: Honda

Vehicle Information: 2000 Honda Accord EX 3.0L

Issue + Repair History:

• Customer complaint of engine hesitation and stalling after a hot restart.
• Issue not replicated by the technicians during testing.
• No error codes found; P0000 (no failure) was the only code displayed.
• Vehicle sent to a local Honda dealer for further diagnosis.

Suggestions to Fix Issue:

• There is a service bulletin for this specific issue involving PCM replacement, fuel regulator, and more (Operation # 124102).
• Check fuel pressure during the problem; a drop below 30 psi suggests a bad main relay.
• Inspect the ignition switch for potential issues.
• Replace ECU and fuel pressure regulator as per TSB for winter gas in warmer climates.
• Ensure the use of NGK spark plugs.
• Perform a secondary voltage test when the vehicle is hot, checking for bad ignition coil or igniter.
• Inspect for dirty intake, clogged catalytic converter, or engine vacuum issues.
• Consult with a Honda dealer regarding the TSB titled “Hard start after hot soak” for potential PCM and fuel pressure regulator replacement.

Final Fix:

• The vehicle was sent to a local Honda dealer due to the potential need for PCM replacement and fuel pressure regulator as suggested in the TSB.
• No conclusive fix was confirmed in the follow-up.

Advice	Brief Description of Diagnostic Step
Verify Scanner and Software	Ensure that the diagnostic scanner and its software are up-to-date and functioning correctly.
Recheck for Codes	Double-check the vehicle with the scanner to see if any specific codes were missed.
Inspect Wiring and Connectors	Check the vehicle’s wiring and connectors for any signs of damage or loose connections.
Check Related Components	Inspect related components such as sensors, fuel system, and ignition system for faults.
Consult Technical Service Bulletins (TSBs)	Look for any TSBs or recalls that might be related to the issue.
Seek Professional Diagnosis	If no specific faults are found, consider a professional diagnostic service for a thorough check.