In newer vehicles, the computer monitors the emissions system to make sure there are no faults. If the monitors don’t function as expected, you will have trouble passing an emissions test and might replace components that aren’t even bad. This is what one customer experienced before they brought their 2005 Nissan Altima SE-R 3.5L into this technician’s shop. With the help of a fellow SureTrack community member, see how this tech was able to solve this issue.

Diagnosis

When the customer came in they informed the technician that they did try to fix the issue by replacing both of the upstream sensors with new Bosch sensors. The technician took it on a 100-plus mile drive cycle; however in the days following, the monitor was still not ready. While he was driving, he checked the data stream and found that the downstream sensors were okay when switching from rich to lean. The tech also observed that the upstream ratio sensor bank 1 stayed at .300 to .350 mv, while the bank 2 sensor stayed between .550 to .650 mv.

Still unsure what the issue could be, he turned to a fellow SureTrack community member. The community member responded by mentioning that he remembered Nissan had some pretty long, detailed drive cycles, and if they weren’t followed, it would not run. Also, he had experience with one vehicle where the power-train control module (PCM) was bad which caused the O2 monitor to not complete.

Fix

Taking the advice of his fellow member, he checked the connections to the sensors and the temperature, and he decided to replace the PCM. He took the Altima for a test drive, and after 15 miles, the oxygen sensor became ready. A thankful technician was able to provide another great fix for their customer.

Real Fixes from Mitchell 1’s SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read the Real Fix in the Mitchell 1 ShopConnection Blog.