Dealing with a car that stalls, especially when accelerating, can be incredibly frustrating. This was the exact problem faced with a 2000 Nissan Altima, signaled by the dreaded “Service Engine Soon” light. Initially, the car would start, but stall again under load or acceleration. Seeking answers, the first step was to use an OBD2 scanner to pull error codes and understand what might be triggering the issue. This experience highlights the common challenges and solutions when using a car scanner to diagnose engine problems, and even addresses a peculiar situation where the scanner itself seemed to cause a no-start condition, requiring an ECM reset.
The journey began with a friend’s OTC scanner. Connecting it seemed like the logical first step to decipher the “Service Engine Soon” light. However, after this initial scan attempt, the Altima refused to start at all. It would crank, but not ignite – a step backward from the initial stalling issue. No error codes could be retrieved at this point, adding to the mystery.
After letting the car sit overnight, surprisingly, it started again the next morning. Basic maintenance steps were taken: a fuel filter and oil change. For a day, the Altima ran smoothly, offering a glimmer of hope. Unfortunately, the stalling issue returned the next day while being driven.
Driven by the need for a reliable diagnostic tool, an Ancel 410 OBD2 scanner was purchased online. While waiting for its arrival, further online research into potential causes for stalling led to a crucial discovery: a vacuum hose, visibly chewed, likely by a rodent that had taken residence in the engine bay during winter. Removing the remnants of a rodent nest and replacing the damaged vacuum hose seemed to address the stalling problem. The “Service Engine Soon” light remained on, but the car was running normally through several test drives. It appeared the vacuum leak was the culprit behind the stalling and the warning light.
With the car running again, the friend returned with his OTC OBD scanner to finally read the error codes. This time, it worked, retrieving a series of codes: P0100, P0505, P0325, P1490, P0446, and P0464. These codes pointed to various potential issues, including Mass Air Flow Circuit Malfunction (P0100), Idle Control System Malfunction (P0505), Knock Sensor 1 Circuit Malfunction (P0325), Evaporative Emission Control System Leak Detection Pump Module Circuit (P1490), Evaporative Emission Control System Vent Control Circuit Malfunction (P0446), and Fuel Level Sensor Circuit Range/Performance (P0464). However, a perplexing situation arose once more: connecting the OBD scanner, even after the car was running well, caused it to not start again. The very act of scanning seemed to trigger a no-start condition, even with the “Service Engine Soon” light still illuminated.
Further investigation online revealed a possible explanation: some OBD2 scanners can, in rare cases, interfere with the car’s Engine Control Module (ECM), requiring a hard reset. The solution? A hard reset of the ECM. This involves disconnecting both battery terminals and then briefly connecting the disconnected positive and negative cables together (ensuring they are completely detached from the battery posts). This process discharges capacitors in the ECM, effectively resetting it. After performing this ECM reset, the Nissan Altima started once again.
This experience underscores several key points for anyone troubleshooting car issues:
- OBD2 scanners are invaluable tools: They provide crucial insights into vehicle problems by reading error codes and offering a starting point for diagnosis. Even a relatively affordable scanner like the Ancel 410 can be beneficial.
- Vacuum leaks can cause significant engine problems: A simple chewed vacuum hose can lead to stalling and trigger the “Service Engine Soon” light. Visual inspection of hoses is a worthwhile step in troubleshooting.
- Scanners can sometimes cause unexpected issues: While rare, OBD2 scanners can, in some instances, cause ECM interference leading to a no-start condition.
- ECM hard reset can resolve scanner-induced issues: Knowing how to perform an ECM reset by disconnecting and briefly connecting battery terminals is a useful troubleshooting technique.
While the term “Mill Off Car Scanner” might be a less common way to describe using a scanner to turn off the malfunction indicator lamp (MIL), the core function remains the same: to diagnose issues and potentially clear codes after repairs. In this Nissan Altima case, the scanner played a vital role in identifying underlying problems, even amidst the unexpected scanner-related setback, ultimately leading to a resolution and getting the car back on the road.
