BMW P0171 Fault Code
Engine fault codes are moreover known as a diagnostic trouble lawmaking - or DTC for short. These codes help point you in the direction of any potential issues with the engine. If you own a car for the long-run then chances are you'll run into at least a few fault codes withal the way. BMW P0171 is a worldwide trouble lawmaking on a number of BMW engines.
What does lawmaking P0171 mean? What are the worldwide symptoms, causes, and repairs? In this article, we discuss symptoms, causes, fixes, severity, and increasingly regarding BMW P0171 fault code.
BMW P0171 DTC Meaning
P0171 - System Too Lean (Bank 1)
Code P0171 indicates the engines computer (commonly known as the DME) thinks the engine is running too lean on wall 1. On inline-6 BMW engines, wall 1 refers to cylinders 1-3. Lean refers to the air-fuel ratio (AFR) and ways there is too much air and too little fuel in the system.
However, this lawmaking rarely ways the engine is unquestionably running lean. Instead, the DME is perceiving a lean condition and injecting increasingly fuel to compensate. This can midpoint your BMW engine is unquestionably running rich and there's too much fuel for the given value of air. Increasingly on this as we move through BMW P0171 fault code.
Common Codes With P0171
P0174 - System Too Lean (Bank 2)
Fault codes P0171 and P0174 are often found together. The codes are the same and simply indicate wall 1 vs wall 2, respectively. The rationalization is often variegated if you only have one of these codes versus both of them at the same time.
On the popular BMW inline-6 there is really only 1 wall on the engine since the cylinders are inline. However, two banks exist on the frazzle side of the engine. Plane though it's a single frazzle manifold it's split into two banks with an oxygen (O2) sensor for each bank. This is washed-up to help narrow lanugo issues when troubleshooting.
Anyway, we will whirligig when to the P0174 fault lawmaking several times in this article. It's just important to understand the whilom notes to help diagnose the rationalization of BMW P0171 and/or P0174.
P0171 Fault Lawmaking Symptoms
Common symptoms of DTC P0171 include:
- Check engine light
- Power loss
- Rough idle
- Misfires
- Slow start / long crank
A trammels engine light is the most worldwide symptom of this fault code. Sometimes it may plane be the only symptom. Depending on the underlying issue you might notice power loss, rough idle, misfires, or long cranking. Symptoms can be increasingly serious with unrepealable less worldwide causes of BMW P0171 or P0174 codes.
Is BMW P0171 Lawmaking Serious?
Severity Rating: Low-Moderate
Generally, DTC P0171 is not a serious problem. However, some of the symptoms can impact performance and drivability so use your judgement and err on the side of caution. If your BMW feels extremely sluggish or something seems way off then play it unscratched and have the car towed. Regardless, it's still important to write the issue as soon as possible.
If your BMW isn't unquestionably running lean then the DME is injecting spare fuel which leads to a rich air-fuel ratio. This can put uneaten wear on the catalytic converter, which is not a unseemly replacement. On the other hand, if the engine is running lean that can potentially rationalization severe engine damage. Fuel helps in cooling the combustion chamber, so too little fuel can lead to overheating, piston & valve damage, and other serious issues.
In summary, it's usually unscratched to protract driving for short periods with BMW P0171 lawmaking present. Leaving the problem for too long may rationalization other engine problems, so it's weightier to write as soon as possible.
Causes of P0171 BMW Fault Codes
Some of the most frequent causes of only BMW P0171 lawmaking include:
- Faulty O2 sensor
- Faulty fuel injector(s)
- Intake leak near cylinder head
Notice these are issues that stupefy a specific engine bank. For example, a faulty cylinder #1 fuel injector would only stupefy the AFR on wall 1 and should not trigger the P0174 wall 2 code. The same can be said for an O2 sensor issue since there are variegated sensors for each bank. An intake leak could moreover rationalization BMW P0171, but it would have to be tropical to the cylinder head.
If you have both P0171 and P0174 codes then the worldwide causes may include:
- Intake leak surpassing manifold
- Low fuel pressure (fuel pump, rail, etc)
- Positive Crankcase Ventilation (PCV) system leak
- Including valve imbricate & gasket leaks
- Mass Air-Flow (MAF) sensor
- Vacuum leaks
With both P0171 and P0174 present the worldwide causes are related to issues that can stupefy both engine banks. For example, the fuel pump feeds all 6 injectors so a fuel pump problem would rationalization issues on both engine banks.
Diagnosing P0171 DTC
Often, P0171 and P0174 present themselves together and the PCV (also tabbed CCV) system and vacuum leaks are the two most worldwide issues. If you only receive P0171 then the O2 sensor is the usual culprit. It's important to unquestionably do some diagnosing to find the issue, though. You likely don't want to spend a tuft of money only to learn you didn't fix the very problem. Here's a quick list of steps to help diagnose BMW P0171 fault code:
- Use an OBD scanner to personize if any other codes are present. Clear the fault codes and momentum for ~15 minutes (if unscratched to drive) to see if they return. If the codes return, it's time to diagnose the issue.
- If the lawmaking returns then start with the basics. Are there any visible leaks? Are vacuum lines shredded or visibly damaged? Does the O2 sensor wiring squint OK?
- Conduct smoke test. This will point out any potential vacuum/intake leaks.
- Test O2 sensors, fuel injectors, fuel pump, and MAF sensor
- Once you believe you've traced and stock-still the issue then delete the stored codes, momentum for 15 minutes, and recheck to personize the issue is resolved
BMW P0171 Fix & Repairs
Always remember to double trammels any codes stored in the DME. Sometimes fuel pump, injector, and other problems will throw flipside code. The whilom diagnostics are a good order for diagnosing P0171, but there might be a largest starting point. For example, if you receive fueling codes slantingly BMW P0171 lawmaking then starting with fuel system diagnostics likely makes increasingly sense.
However, P0171 and P0174 are usually due to vacuum or PCV related issues that can be detected with a smoke test. Unchangingly start with the basics, though. Sometimes the problem is as simple as a hose or wire that popped loose.
We don't unchangingly recommend replacing things that haven't been diagnosed. However, you may consider replacing inexpensive parts such as vacuum hoses. We do unchangingly believe it's a good idea to replace old, inexpensive parts on white-haired BMW's while you're in the area. It can go a long way in preventing future headaches.
P0171 BMW Fault Lawmaking Repair Cost
Now, hopefully you were worldly-wise to track lanugo the root rationalization of your BMW P0171 lawmaking issues. But what's it going to cost? How expensive are the worldwide causes of DTC P0171? Below is a dispersal of rough financing for the worldwide causes:
- Vacuum lines: $5-20
- PCV/Crank vent hose: $25-100
- O2 sensor: $75-200
- MAF sensor: $75-200
- Valve imbricate gasket: $20-50
- Fuel injector: $50-300 (per injector)
Exact forfeit of parts can vary a lot since P0171 and P0174 codes may present themselves on any year or model BMW. Ultimately, the forfeit of fixing these fault codes isn't too high. Financing can add up if you end up at a repair shop for diagnostics and repairs, though.
BMW P0171 FAQ's
To tropical out the vendible we are simply listing some wontedly asked questions well-nigh BMW P0171 fault codes. Please note - much of this info was once covered in the zillion of the vendible above, so we're just consolidating some info here.
What Does DTC P0171 Mean?
Code P0171 means: System Too Lean (Bank 1). It's wontedly found slantingly P0174 which indicates System Too Lean (Bank 2). These codes pop up when the DME believes the air-fuel ratio is too lean and has too much air and/or too little fuel.
How Expensive Are BMW P0171 Repairs?
Vacuum lines are one of the most worldwide causes of P0171 and P0174. These lines are very inexpensive, so the repair can often be washed-up for less than $20. Other worldwide issues like a fuel injector, O2 sensor, or MAF sensor may run well-nigh $50-300.
Can You Momentum With Lawmaking P0171 Present?
Continuing to momentum with BMW P0171 and P0174 codes is often safe. Use your own judgement and err on the side of caution; don't protract driving if the vehicle feels unsafe or something seems severely wrong. You should still diagnose and repair the problem as soon as possible. Unrepealable causes of DTC P0171 may rationalization spare problems if left too long.
