This reference guide provides a comprehensive overview of On-Board Diagnostic (OBD) testing, specifically focusing on Check Engine Code Obd2. We’ll explore pass/fail criteria for Smog Check inspections and offer guidance for vehicles known to have OBD2 testability issues. Understanding these codes is crucial for effective vehicle maintenance and ensuring your car passes emissions tests.
Understanding OBDII Readiness Monitors
Your vehicle’s OBD2 system utilizes readiness monitors, self-diagnostic tests that evaluate the performance of emission control components. While regular driving typically allows most vehicles to complete these monitors, certain driving conditions or infrequent use can hinder their completion. Occasionally, owner’s manuals provide specific driving procedures, but often, this information is exclusive to the manufacturer or available in professional automotive repair resources. These “drive cycles” require specific operating conditions (speed, temperature, pressure, engine load). Replicating these conditions in traffic can be challenging but is possible with dynamometer equipment. Proper component function is also vital; a faulty component may prevent monitor completion until diagnosed and repaired. Activities like battery disconnection or component replacement necessitate rerunning readiness monitors.
OBDII Monitor Completion Requirements
The table below outlines the allowable number of incomplete OBD readiness monitors for passing a Smog Check inspection, categorized by vehicle model year and fuel type. This information is crucial for understanding your check engine code obd2 results.
| Model Year | Fuel Type | Number of Incomplete Monitors Allowed to Pass OBD Test |
|---|---|---|
| 1996-1999 | Gasoline1 | Any one2 |
| 2000 and newer | Gasoline1 | Evaporative System2 |
| 1998-2006 | Diesel | Zero |
| 2007 and newer | Diesel | Particulate Filter and Non-Methane HydroCarbon (NMHC)3 |
1 Includes gasoline, propane, natural gas (CNG, LNG, LPG).
2 The misfire, fuel, and comprehensive component continuous monitors are disregarded for gasoline vehicles during an OBD test.
3 Implemented July 5, 2023.
Check Engine Light (MIL) and Communication Standards
The Malfunction Indicator Lamp (MIL), often referred to as the “Check Engine” light, plays a critical role in OBD2 diagnostics. Its behavior during the key-on, engine-off (KOEO) and key-on, engine-running (KOER) stages indicates potential issues. A check engine code obd2 reader will be necessary to diagnose the specific issue.
MIL and Communication Pass/Fail Criteria
| Vehicle | Pass/Fail | Standard |
|---|---|---|
| All with OBDII | Pass | MIL illuminates during KOEO |
| All with OBDII | Pass | MIL turns off during KOER |
| All with OBDII | Fail | MIL does not illuminate during KOEO |
| All with OBDII | Fail | MIL illuminates during KOER |
Additionally, successful communication between the vehicle and the testing equipment is essential. Failure to communicate can stem from various factors, including a damaged OBD2 connector, wiring problems, aftermarket stereo installations, or invalid data transmission.
| Vehicle | Test Type | Standard |
|---|---|---|
| All with OBDII | BAR-97 | Vehicle communicates with BAR-97 equipment |
| All with OBDII | OIS | Vehicle communicates with OIS equipment and transmits required data1 |
1 Required data generally includes data from specific OBD addresses indicating supported data, MIL status, Diagnostic Trouble Codes (DTCs), and monitor status.
Permanent Diagnostic Trouble Codes (PDTCs)
Introduced on July 1, 2019, to the BAR-OIS Smog Check, Permanent Diagnostic Trouble Codes (PDTCs) function similarly to regular DTCs but persist even after DTC clearing procedures. Only the OBDII system can clear a PDTC after confirming the resolved issue. These codes are crucial for understanding persistent check engine code obd2 issues.
PDTC Pass/Fail Standards
| Model Year | Test Type | Standard |
|---|---|---|
| 1996-1999 | BAR-97 | Not Applicable |
| 2000-2009 | OIS | Not Applicable |
| 2010 and newer1 | OIS | Vehicles fail with a present PDTC2,3,4,5 |
1 Some 2010 models lack PDTC support and are exempt from this check.
2 A stored PDTC results in failure regardless of MIL status.
3 PDTC presence is ignored after 15 warm-up cycles and 200 miles driven since the last OBD information clearing.
4 Known PDTC clearing issues in certain vehicles are being addressed in collaboration with the California Air Resources Board (CARB).
5 Manufacturer warranties, recalls, and repair campaigns exist for some vehicles with PDTC clearing problems.
Modified Software and Vehicles of Interest
Vehicles with illegally modified software will fail the Smog Check inspection. The inspection report will indicate “Modified Software” as the reason for failure. To pass the retest, the vehicle must be restored to its original manufacturer-approved or CARB-approved software configuration.
Specific makes and models are known to have recurring issues with the OBD test portion of the Smog Check inspection. These issues can range from communication failures to incomplete readiness monitors. Refer to Section D and Section F of the original document for a detailed list of these vehicles and their specific issues. This information will assist in diagnosing and resolving problems that may trigger a check engine code obd2. Consult a qualified mechanic if you encounter these specific issues.
Conclusion
Understanding the intricacies of check engine code obd2 testing, including readiness monitors, MIL status, communication protocols, and PDTCs, is vital for vehicle owners and technicians alike. This knowledge allows for accurate diagnosis, effective repairs, and successful Smog Check inspections. Always consult official manufacturer resources or a qualified mechanic for vehicle-specific guidance and repair procedures.
