Experiencing car trouble can be frustrating, especially when your vehicle decides to stall unexpectedly. For a 2000 Nissan Altima owner, a stalling issue quickly escalated into an even bigger headache involving a diagnostic scanner and a no-start condition. This is a firsthand account of troubleshooting a perplexing car problem and exploring the question: can a car scanner short out the onboard computer?
The initial problem began with the car stalling, particularly during acceleration or under load. Despite stalling, the engine would restart, only to stall again. The “Service Engine Soon” light was illuminated, signaling underlying issues. Hoping to diagnose the problem, the owner enlisted the help of a friend with an OTC scanner. However, after connecting the scanner, a new problem arose – the car wouldn’t start at all. Cranking but refusing to ignite, and with no error codes retrievable, the situation seemed to worsen after the diagnostic attempt.
After letting the car sit overnight, a surprising turn of events occurred: the car started again. Basic maintenance steps followed, including a fuel filter and oil change. For a day, the Altima seemed to run smoothly, leading to a false sense of resolution. Unfortunately, the stalling issue returned, this time while the owner’s daughter was driving. Determined to get to the bottom of it, the owner invested in a personal OBD2 scanner, an Ancel 410, ordered online.
While waiting for the new scanner, online research pointed towards a potential culprit: a vacuum leak. A closer inspection revealed a chewed vacuum hose, likely the work of a rodent that had previously nested in the engine bay. Replacing the damaged hose seemed to resolve the stalling issue. Road tests confirmed smooth running, although the persistent “Service Engine Soon” light remained on. It appeared the vacuum leak was the cause of the stalling and the warning light.
With the car running again, the friend returned with the OTC scanner to finally read the error codes and address the lingering “Service Engine Soon” light. This time, the scanner successfully retrieved several codes: P0100, P0505, P0325, P1490, P0446, and P0464. However, history repeated itself. Connecting the OBD scanner again resulted in the car refusing to start. The very act of connecting the scanner seemed to have triggered the no-start condition once more, even after the car was running fine.
Further online research revealed a possible explanation: OBD2 scanners can, in some cases, interfere with the car’s Engine Control Module (ECM) or Powertrain Control Module (PCM), essentially the onboard computer. The solution suggested was a “hard reset” of the ECM. This involves disconnecting both battery terminals and then briefly connecting the disconnected cables together (away from the battery) for about 10 seconds. This process discharges capacitors in the ECM, effectively resetting it.
Following these instructions, the owner performed a hard reset. The result? The Nissan Altima started again. While the initial stalling was traced to a simple vacuum leak, the intermittent no-start issue seemed directly related to using an OBD2 scanner. While it’s not a common occurrence for a scanner to “short out” an onboard computer in the traditional sense of causing permanent damage, it appears they can sometimes disrupt the ECM’s operation, leading to a no-start condition that a hard reset can resolve. This experience underscores the importance of understanding potential interactions between diagnostic tools and your car’s computer system.
