This month, we’ll be taking a look at the Nissan line and some of the common causes for the check engine light to be lit, as well as some of the driveability problems that may result.
We’ll start with the popular Altima model that enjoyed a third-generation makeover in 2002 one that really increased its popularity. One of the most common problems you’ll see with these cars is a P0335 code that represents a problem in the crankshaft position sensor circuit, sometimes accompanied with a P0755 engine speed code. This problem was identified early on, with Nissan issuing a recall that involved replacing both the camshaft and crankshaft sensors, as well as reflashing the ECU. That recall took care of many of the earlier cars, but the problem still persists as the cars get older.
Early on, we were changing both sensors whenever the code was encountered, but we have since changed our strategy to replacing only the crank sensor when that code is evident. The sensor is located on the firewall side of the engine and, while not easy to reach, presents little challenge when installing. There is one important thing to keep in mind and that is to be sure to plug the harness onto the sensor before installation, as it can’t be done afterward without modifying the connector. And, like any code issue, keep in mind that the code is not part specific, so be sure to take a look at the connector and wiring while you’re there. As you would expect, crank sensors failures have led to intermittent no-starts and long-crank complaints.
While the majority of these complaints end up being sensor issues, remember that these sensors are also looking at the relationship between the crank and cam position. There have some reports of loose timing chains and faulty variable timing camshaft sprockets resulting in this code. This possibility exists if you’re looking at a high-mileage car, or if there is any noise from the timing chain area. Another giveaway is when a vehicle has had both sensors changed and the problem persists. While there have been some reports of defective sensors out of the box, it’s been our experience that OEM sensors rarely have that issue.
Another fairly common issue on the Altimas is catalytic converter failures. Again, the older cars were taken care of with recalls or factory involvement, but as the cars age and the mileage builds up they’re finding their way to our bays. The problem with the 2.5 L four cylinders is that as the manifold-mounted converter fails, debris from the converter can be drawn into the cylinders causing damage to the valves and rings. This is why we always recommend not putting off replacing a converter that is failing.
IDLE CONTROL PROBLEMS
Another area that seems more prone to problems on the Altimas is the electronically controlled throttle body and P0507 code. After years of including a good throttle body cleaning in a service, we’ve found it best to leave the drive-by-wire electronic units alone.
If you’re faced with a car that is having idle problems or setting a throttle body code, the first step is to perform a Throttle Relearn procedure, also known as Idle Air Volume Learning procedure. If you’re lucky enough to have a scanner with OEM capabilities, that is by far the easiest way to perform this service; if not, there is an alternate method available using the check engine lamp and throttle.
There are a set of parameters that have to be met to perform this service and, again, a scanner that can read transmission fluid temp, coolant temp and battery voltage would help here, otherwise you could rely on a 10-minute road test. With the parameters met, turn off all accessories and the key for at least 30 seconds; setting the handbrake will keep the daytime running lamps off.
Be sure the accelerator pedal is released. Turn the key on/engine off, and after three seconds fully open and release the accelerator pedal five times, wait seven seconds to fully depress the accelerator pedal and hold it until the check engine lamp stops blinking and comes on solid.
Start the engine and let it idle for 20 seconds, and then rev it up a couple of times being sure it returns to a smooth idle within the specs as listed. This procedure can be challenging to perform but should be done whenever the ECU or throttle body is replaced or a code is set.
Moving to the top-of-the-line Maxima model, we see some of the same problems with different symptoms and systems that are involved. While not really a crank sensor problem, you may be presented with a car that cranks as if the ignition timing is over advanced; the issue is the routing of the main ground cable over the crank sensor. A thorough cleaning of the connections will take care of the problem, but we’ve had better success rerouting the ground cable to one of the starter mounting bolts, ensuring a solid connection with no current leakage to confuse the sensor. This particular problem won’t set a code.
If you’re faced with a P0011 or P0021 code indicating intake camshaft timing control, don’t jump to replace the sensor as this code indicates that the target timing wasn’t reached as expected. All the ECU knows is that it told the cam timing solenoid to open and expected the resulting oil pressure to change the timing; when the position sensor didn’t report a change, the code is set. If the ECU wasn’t seeing the cam, or the phase sensor as Nissan calls it, it would have set a P0340 or P0345, depending on the affected bank.
If you’re looking at a P0011 or P0021, your first thought should be to check the oil level and condition and, if all is well, use your service info to diagnose and repair the system. The solenoids appear reliable with most problems being traced to sludge buildup, either in the solenoid screens with some problems reported with camshaft sprockets. We always have to keep in mind that the engine control system always assumes the engine is in good mechanical condition.
A P0340 or P0345 is an indication that the ECU didn’t see a signal from the cam sensor as expected. There are two setting conditions that will set this code. There is the engine cranking test where the engine is cranked for two seconds and the ECU did not detect a normal pattern of CKP sensor signals, and the engine running test where the ECU did not detect any cam position signals or it detected an abnormal sensor pattern. In the event of a crankshaft position sensor failure, the ECU will look at the cam sensor for the inputs needed.
When it comes to idle control issues, we see more problems on the older cars that pre-date the drive-by-wire system. On these cars, the problem is more of a cold- start idle problem or stall with a P0505 IAC code. Again, you’re ahead of the game with a scanner that offers the capability to let you set the idle by increasing the IAC opening. If the idle responds to the adjustment, you know the system is working and it would pay to look for a vacuum leak, unmetered air or a dirty throttle housing that would be causing the idle problem. If the IAC doesn’t respond, go to your service information and check the IAC for a shorted segment. If a short is found, it’s a good bet the ECU has been damaged and will need to be replaced along with immobilizer flashing.
The drive-by-wire Maximas aren’t immune to idle problems, and they share some of the same problems that the Altima does, but they don’t seem to be as prevalent as they are on that model. One tip that is mentioned in the service bulletin for the Maxima is the suggestion that injectors be unplugged to lower the idle if the relearn doesn’t complete and the car in question is idling high.
On the four-cylinder cars, you can unplug up to two cylinders, and three on the sixes (not all on the same bank). Be sure to clear any misfire codes induced once the relearn is completed.
MASS AIR FLOW & IGNITION COIL ISSUES
A bad mass air meter is another problem that can affect the idle as well as overall performance and seems to be more common with the Maximas, but one that you’ll see on all the models. Some of these can be tough to diagnose; the dirty ones can be picked up by looking at calculated load during a wide open throttle uphill pull. It gets a bit trickier with the intermittent cutouts and stalls when coming to a stop. If you have a vehicle with those complaints and can confirm good, consistent fuel pressure, suspect the air mass; if there’s a P0100 code associated with the complaint, I’d be recommending a replacement.
Another problem that was common on the older cars was ignition coil failures. If you’re lucky, you’ll get a solid misfire and code but, more often than not, you’ll be faced with a P1320 “Ignition Control Signal Circuit Malfunction” code that isn’t cylinder specific but indicates a coil failure. At this point, you and the customer have a decision to make. Many times, the customer doesn’t have a driveability complaint and it can be a hard sell to replace six coils. Oftentimes, our customers choose to continue to drive the car until the cylinder in question throws a misfire code rather than replace all six coils as Nissan recommends.
EVAPORATIVE EMISSION SYSTEM ISSUES
Moving to the affordable Sentra model, we see some of these same issues, but it seems this model is more prone to problems with the evaporative emission system than the other models. Nissan uses an electrically controlled vent valve that has been known to fail in both directions. The most common is a valve that won’t close and leads to a P01352 large leak code, but diagnosing this canister-mounted valve is straightforward. Many scanners have the bi-directional controls that will let you command the valve closed, where you can hear the valve close solid; if you don’t have an enhanced scanner, grab your two-wire test light or jump leads and apply power and ground to operate the valve.
It’s been our experience that the valves don’t tend to be intermittent, but keep in mind they can fail either way and be stuck open or shut. So if you’re faced with a slow-filling or difficult-to-fill fuel tank, suspect a valve that’s stuck closed.
It also pays to be careful when estimating the job to make sure the valve can be removed from the canister before you give the final price. The valve is bolted to the canister and lives in a bad environment, so it’s not uncommon for the bolts to break or the nuts that are captured in the plastic canister to spin, forcing you to replace the canister. It’s better to check beforehand, rather than call your customer later with a surprise.
That’s not to say the Sentras or any of the Nissans for that matter can’t suffer from some of the same leak problems in the evaporative system that you’ll see on any other car. While the vent valve is a common failure, beware of canisters that have cracked and rust-damaged filler necks; your smoke machine will certainly pick up these failures.
The Sentra also had a recall on those troublesome crank and cam sensors. As with other models, these sensor failures aren’t uncommon. What we do see a bit more with the Sentra 1.8 L engine are mechanical problems with timing chains that cause sensor codes. Most times, there are driveability complaints along with the check engine lamp; just keep in mind that a sensor code can be caused by a jumped timing chain. Many times, the customer is more aware of the service engine lamp than the lack of power.
The same thing applies to head gasket failures; a mysterious misfire code may start making more sense as you notice that the coolant level is low or you pick up that slight “miss” when you start the car cold. We have covered head gasket diagnosis and replacement on the 1.8 L in the past, and it is available on the ImportCar website.
With solid parts availability and a wealth of knowledge just a couple of mouse clicks away on web-based resources, like the ImportCar website, iATN and other technician community forums, there is no reason to shy away from these cars.
It’s obvious that technology is moving forward and we have to be equipped to handle whatever comes our way. That means we have to consider making the investment in the proper equipment, plus we have to be in a position to handle this type of work. It’s very difficult to repair and diagnose systems that you don’t understand, so take the time to read every article you can find both in print and online that will help you get a handle on these new technologies. The time invested in keeping up with technology pays dividends for both your shop and your customers.