The 4 Most Common Problems with BMW’s N53 Engine

The BMW N53 engine was produced from 2006-2013.  It is the last of a tradition from BMW that dates back to 1968.  The naturally aspirated straight six has been a major component to BMW's formula, which also includes rear wheel drive, and near 50/50 weight distribution.  Based on extensive research, there are some notable common issues with the N53 but overall it is very reliable engine.  Let's go over the 4 common problems with the BMW N53.

History and Models

Fitted in BMW E9x 3series, E60 5 series and even the F10 5 series until 2011.  The N53 replaced the N52 in most markets, except for notably the North American Market and Australia.  These markets were excluded due to high sulfur content in the fuel.  BMW was able to reduce fuel consumption in the N53 engine by adding direct injection and a nitrogen oxide storage catalytic converter.  This catalytic converter required low sulfur content fuel to run properly.  While most markets got the updated BMW N53, the U.S., Canada, and Australia continued to get the N52.

4 Common Problems with the N53 Engine

1. Fuel Pump
2. Injectors
3. Spark Plugs
4. Coil Packs

1) N53 High Pressure Fuel Pump (HPFP)

This is the first common and most prevalent issue to come up with the N53.  High Pressure fuel pumps were such an issue when the engine first came out that BMW issued a recall on the engine. The N53 uses the same HPFP as the BMW N54, and these issues are well documented.

Symptoms of N53 HPFP Failure

• Long crank
• 1/2 engine light
• Rough idle
• Stuttering acceleration

When the high pressure fuel pump is failing it will not deliver enough fuel to the engine for proper operation. The lack of fuel flow is what causes long cranks, rough idling, and stuttering while accelerating.  The 1/2 engine light may illuminate and the car will likely continue to drive until the HPFP completely fails and does not flow adequate fuel for the engine to fire.

Mileage for Failure

High pressure fuel pumps on the BMW N53 may fail at any mileage; many likely failed early on and were replaced under the recalls and extended warranty.  In 2012/2013, after multiple attempts, BMW finally re-designed the HPFP which seems to have resolved the issues. If you are looking into purchasing a model with the N53, be sure to check the maintenance records to ensure the HPFP has been replaced either by recall or by the previous owner.  Most N53 HPFP's likely experienced failure early on and received the updated fuel pump, but there may be a few out there still running the original faulty part.

2) N53 Fuel Injector Failure

The N53 went from port injection to direct injection with Piezo injectors (similar to the BMW N54).  With this change, came a learning curve and lots of changes and reprogramming to these parts.  Though the BMW N53 and N54 both used direct injection featuring Piezo injectors the actual part number and injectors were different on each engine.  Despite this difference, they suffered a similar fate with common failures.

Symptoms of N53 Fuel Injector Failure:

1. Misfires
2. Limp Mode
3. Rough Idle
4. Poor Fuel Economy
5. Check Engine Light

Unlike the HPFP issue that does not flow enough fuel, the injectors typically fail by developing leaks and dumping extra fuel into the cylinders.  This extra fuel causes misfires, rough idle, poor fuel economy and potentially check engine lights and limp mode.

If you do need to replace the injectors, do not buy them refurbished or used, and try to get them to match the same index.  The newer fuel injectors that fixed the early issues have different indexes; it is important to note that different index fuel injectors can not be mixed on the same bank (i.e. cylinders 1-3 or 4-6).  After replacement, they will need to be coded.  Not replacing them properly can cause the engine to still run rough, which may lead into the next two issues.  These 3 of the 4 common N53 problems have to do with misfires and rough idles.

3) N53 Spark Plug Failure

Not a huge issue on the BMW N53, but something I saw come up several times with owners attempting to correct their misfire and rough idle situation.  The spark plugs have been known to wear prematurely, causing misfires and rough idles. Leaking fuel injectors dump extra fuel near the spark plug tips causing premature wear.  Also, if you have or had a valve cover gasket leak, there is a chance that oil has soaked into the plugs.

Symptoms of Bad N53 Spark Plugs

• Rough idle
• Stuttering acceleration
• Loss of power & torque
• Reduced engine responsiveness

In addition to premature wear, spark plugs naturally wear down over time and become less effective or faulty, causing the same symptoms above. They should be replaced roughly every 40,000-50,000 miles, and are a cheap repair that can easily be completed by novice DIY'ers. If you know your spark plugs have not been replaced in that time frame it may be a good idea to knock out the repair as preventative maintenance.

4) N53 Bad Ignition Coils

Another BMW N53 issue causing power loss, misfires and rough idles (same or similar symptoms as spark plugs).  The coil packs are usually an overlooked issue.  It seems most owners report this as the last item they replace after the injectors, and spark plugs to fix the misfires and rough idles.  While it is difficult to diagnose with certainty, getting to the coils is relatively easy; they actually sit on top of the spark plugs and must be pulled out to replace the spark plugs.   If the engine has over 50,000 miles (or if they have not been replaced in the last 50,000 miles), chances are the ignition coils may be faulty or under-performing.

Summary

Compared to other engines in the BMW lineup, I would say this engine is reliable and ready for a long life.  Considering these 4 common issues with the N53, there are no major issues with oil leaking or with the cooling system which tend to end the life of the engine. Of course, older engines with high mileage may develop oil leaks or other issues as a part of standard wear and tear, though they are not overly common issues.  A fuel pump may put you in limp mode, but will not retire the car to the junk yard.  Same goes with for the injectors, spark plugs and coil packs.

Reliability score 1-4 with 4 being the worst: 1

BMW produced a fantastic engine to make its mark as their last naturally aspirated engine.  Let me know what you think of the engine if you own one or your experience with it.

If you liked this post, check out our article on the N63.