Here’s another precaution Nissan warns about: Don’t attempt to jump-start the vehicle if it has run out of gas. After hooking up the jumper cables to the positive stud in the fuse box and a body ground in the engine compartment, push the start/stop button twice but without touching the brake pedal. This will prevent the system from going to READY status, but will display the fuel level. If the fuel level reads low, add four or more gallons of gas to the tank before attempting to start the vehicle in the normal manner. When the READY light is on, stepping on the gas will automatically start the engine to begin recharging the battery(s).
If the 12V battery needs to be recharged, do not use the lug in the engine compartment because the power here is routed through some control electronics that could be confused or damaged by a charger. Nissan says to hook up your charger directly to the 12V battery in the trunk (after removing its cover panel). Nissan also says to use only a 5-amp trickle charger. Do not use a quick charger or booster charger as this may damage the vehicle’s control electronics.
If the original equipment Panasonic 12V battery needs to be replaced, use a gel cell Optima battery, rather than a conventional liquid acid cell battery. The charging characteristics are somewhat different, and the voltage is just a bit higher with the gel cell Optima battery. A standard battery may confuse the hybrid control electronics and result in overcharging problems.
The replacement 12V battery should be positioned on the battery tray with the positive terminal to the right as viewed from the back of the car. The replacement battery (Nissan P/N 999MI-NB34C) sits atop a plastic spacer that snaps onto the bottom of the battery.
When disconnecting the 12V battery, make sure the READY light is off. Then disconnect the negative cable first, followed by the positive cable. When reconnecting the battery, connect the positive cable first and the negative cable last. This is necessary so the surge in voltage does not confuse the hybrid control electronics.
There’s one additional step that’s necessary when replacing the 12V battery. The location of the battery positive terminal and cable is very close to a ground strap on the body. Should the battery vibrate loose, it might ground out against the ground strap connection, so Nissan says to apply a small rubber pad or multiple layers of electrical tape over the ground strap connection to provide a protective layer of insulation.
A low 12V battery may also set a code P0603, which is a fault for the ECM power supply. It is usually a false code, and can be cleared using a scan tool. Even so, you should check to see if the code returns the next time the start/stop button is pushed and the system is READY for driving.
If there’s a problem with the 244.8-volt hybrid battery, it’s covered under warranty for 10 years or 150,000 miles.
Nissan warns against driving the vehicle if it has run out of gas. Running in electric mode without engine recharging will quickly deplete the hybrid battery, and may damage it.
One other service note is that the 2007 and 2008 Altima hybrid cars use different air/fuel sensors. If the wrong sensor is installed, it may set an oxygen sensor code. Nissan TSB NTB08-012A says the 2007 A/F sensor part number is 22693-JA00B and it has a black plastic cover over the wiring connector. The 2008 A/F sensor part number is 22693-1AA0A and it has a gray plastic tube cover over its wiring. In some cases, it may be necessary to do a computer reflash if the wrong sensor has been installed.
