This article will take a look at some of the common problems that cause check engine lights to illuminate and/or driveability problems on the popular Nissan line of vehicles. With many states adopting statewide OBD II emission inspections, the days of ignoring the light are over. We’ll look at the popular V6 engine used in every category that Nissan covers. Nissan’s sports cars to minivans and everything in between has had a version of this engine under the hood.

There’s no arguing that this engine has been a homerun for Nissan. It’s hard to believe that it was more than 20 years ago that the VG30 made its debut. It has certainly proven to be a good, reliable engine that will deliver many miles of troublefree service. (While this article covers the V6 engines, the information is relevant to the Sentra, Altima and four-cylinder trucks as well.) Let’s start with some electrical and ignition issues. There have been problems with ignition coils on the later-model twin-cam Nissans that use the coil-on-plug ignition system. In some cases, a P1320 primary ignition signal code is the first indication to you and your customer that there’s a problem with a coil that will soon lead to a misfire code.

There are a couple of directions you can take in this situation. You can check the coils using an ohmmeter, or you can take a look at the coils with your scope or graphing meter using a low-amp probe, if you’re shop is so equipped. The problem with this approach is if the failure is intermittent, you may not pick it up. You have to keep in mind this problem is very subtle (I’ve never had a customer report a driveability problem associated with it.)

Another path is to replace all the coils. While I wouldn’t call it unethical, it’s an expensive way to solve the problem and I just don’t feel right replacing parts that are good; add in the fact that there’s been no pattern of the same car returning with multiple failures, so I don’t recommend this approach.

What works for us is to clear the primary ignition code and suggest to the owner that he drives the car until a misfire code lets us know which cylinder is the problem. While not a high-tech solution, most customers understand and appreciate the lower cost involved in taking this route.

CRANKSHAFT & CAMSHAFT SENSORS
While crank and cam sensor problems are rare on the later vehicles, there is one problem on the 2002 and up Nissans that can be a real challenge. If you’re faced with an engine that sounds like it’s out of time when starting, but runs well once it does, check the battery ground wire routing to see if it’s passing over the crank sensor. If so, simply rerouting the ground to another location will straighten it out. We do this on all cars that get a new starter. We relocate the ground to one of the starter mounting bolts from the original bracket. It’s necessary to enlarge the eyelet on the cable a bit; a quick task for a tapered ream.

There were some reports on the earlier cars of a crank sensor harness problem with a bad connection on the right side near the strut tower. A good visual inspection is all you’ll need to find the problem. Be sure the harness is routed out of harm’s way when you’re done.

We’ve seen some problems with reference sensors on the older Nissans where the sensors are located in the distributor housings. In these cars, the sensors are of an optical design, with the light passing through small windows keeping the ECU abreast of engine speed and piston location. Any debris blocking the windows will cause anything from misfires to hesitations to no-run conditions. When faced with any of these symptoms, it takes only a couple of minutes to remove the cap, rotor and protective cover to do a check. But be careful; those components are fragile and only good-quality rebuilds are available if needed.

This is a good time to give the cap and rotor a good inspection. If you’re in doubt as to their condition, replace them. We’ve had more than a couple of no starts towed in that were either burnt through or had loose rotors or cracked caps that would leak spark when wet.

NO-START CONDITIONS
While we’re talking about no-start conditions, this would be a good time to touch on a few other issues that can be tough if you’re not aware of them. The first has probably caused more wasted time than any other issue on these cars — that is, the key losing its memory and the immobilizer doing its job, preventing the engine from starting. We’ve received numerous calls from shops that were fighting this one. The tipoff is that the injectors won’t be getting a ground signal from the ECU. Actually the best tipoff is the security light flashing on the dash as you try to start the car, but it’s easily overlooked. This will usually require having the car towed back to the dealer for a reprogram, or calling in a well-equipped locksmith if you’re lucky enough to have one available.

The other starting issue that we’ve seen on the mid-’90s cars involves the electrical part of the ignition switch. Nissan, like many other carmakers, uses a bypass-type ignition switch that turns off power to accessories that aren’t required for startup when cranking. The problem comes when the terminal that should have power in the start position doesn’t, but the starter terminal still gets power, so you’re faced with a strong crank and no-start condition. Sometimes, the customer will report that it seems like the car starts when he lets go of the key, but you can’t count on that. The best place to test for this is at the start fuse in the underdash fuse box. With the key in the start position, this fuse should show battery power. If not, it’s a safe bet that the ignition switch is the culprit.

EVAP System Diagnosis
Another common cause for check engine light (CEL) illumination is the Evap system. Setting a generic P0440 code is an instance where having enhanced scanner information can pay dividends by better pinpointing the problem. While the 440 code will get you in the right direction, the job will be made easier with the enhanced software that provides more information as to where the problem lies within the Evap system.

In the case of the Nissan, the most common problem by far is the vent valve mounted on the canister. This normally open valve is commanded closed by the ECU when the leak test is performed. As you’d expect, if the valve is stuck open it’s seen as a leak, the CEL is turned on and a code is set. In the event the valve sticks closed, the customer will report problems with filling the tank. While tank implosion could take place, we haven’t seen any. Confirmation diagnosis is straightforward — grab your power probe and apply power and ground to the easily accessible valve and listen for movement. While you’re there, be sure the mounting bolts come out of the canister before you order parts. Again, if you have Nissan-specific software, the valve can be commanded to close using bi-directional controls, which not only makes the job that much easier, but also confirms the integrity of the circuit.

As the miles build up, you may also see some EGR flow codes. On the earlier models, there were some problems with the hose that sent exhaust backpressure to the transducer on the intake manifold. This problem was most common on the Quest minivans. While difficult to see because of packaging, it’s easy to feel the damaged hose. If replacement is required, be sure to use a hose that will stand up to the heat. This is also a convenient spot to check exhaust pressure should you suspect a clogged catalytic converter.

You can suspect carbon buildup in the tube between the EGR valve and the intake manifold on all models. You’ll find the most severe blockage where the tube mounts to the intake, but be sure to also clean out any buildup in the tube.

We’re also seeing a good amount of catalytic converter efficiency codes on the high-mileage cars. It’s not unusual to see these cars with well over 100,000 miles on them, so it’s not much of a surprise that the miles can take their toll. It’s usually the bank one or firewall side converter that’s the problem, but, either way, don’t remove the scanner without taking the time to look at the front and rear O2 sensors in current data.

If they are mirroring one another, you’ve confirmed the problem and can sell the job with confidence, and have some idea how well the sensors are working. To get the best information available, always limit the parameters in display to the sensors in question. While Nissans communicate well, you’ll get faster information when you ask for less.

SENSOR ISSUES
Just like any other car, Nissan has its fair share of sensor problems. I’m sure we’re all experienced in confirming O2 problems, but I will remind you that we have to keep in mind that any code is circuit- or system-specific, not sensor specific. If you have an O2 heater code, be sure the circuit is intact and current is available before replacing the sensor.

Nissans have the same issues with air mass sensors that other carmakers do. While a bad one will set a code, you’ll almost certainly have the familiar driveability complaints. With 20 years of experience under our belt, we should all be familiar with diagnosing these units. Diagnosing these components has become easier with the increased use of labscopes and graphing meters. You can still use the “unplug it and see if it runs better method” on severe cases, but if you’re looking at a system lean code where the problem will be more subtle, you’ll certainly need the upgraded equipment.

The last thing I want to mention is the very common knock sensor code. This code doesn’t affect emissions and won’t illuminate the engine light. Mounted under the intake, it’s a labor-intensive job that has no apparent affect on driveability. If you’re diagnosing a driveability complaint and there’s no code other than the knock sensor, I suggest you check the things we’ve talked about. Don’t forget the basics — fuel delivery, engine condition and condition of maintenance items all have to be considered.

Many times you’ll be seeing a car for the first time when it comes in for a driveability problem. It’s usually a referral, and very often you’re not the first shop that’s looked at the car. If you can efficiently nail down the problem and get the car back in service for a fair price for both you and your customer, you stand a pretty good chance of earning a loyal customer. I hope this article will help you reach that goal the next time there’s a Nissan in your bay.