Have you ever been driving your Audi when suddenly that dreaded check engine light comes on? If your mechanic or diagnostic tool showed a P17D400 Audi fault code, you might be wondering what it means and how serious it is. Don’t worry! At First Auto Centre, we’re here to explain what the P17D400 fault code means in simple terms that anyone can understand.
What Does the P17D400 Audi Fault Code Mean?
The P17D400 Audi fault code typically points to a problem with the exhaust gas recirculation (EGR) system. This might sound complicated, but we’ll break it down for you.
When this code appears, it usually means:
There’s an issue with how exhaust gases are being recycled back into your engine
Your car’s computer has detected that the EGR valve might not be opening or closing properly
The system that helps reduce harmful emissions from your car isn’t working as it should
This fault code is specific to Audi vehicles and is part of their unique diagnostic system. As an Audi specialist in London, we see this code fairly often and know exactly how to address it.
Why the EGR System Matters
The EGR system in your Audi plays an important role in:
Reducing harmful nitrogen oxide (NOx) emissions
Improving fuel efficiency
Helping your engine run smoother
When it’s not working properly, your car might not run as well as it should, and you could even fail an emissions test. A properly functioning EGR system is crucial for both performance and legal compliance with emissions standards.
Common Symptoms of a P17D400 Fault Code
How do you know if your car has an EGR system problem before checking the fault codes? Here are some signs to watch for:
Your engine might run roughly, especially when idling
You might notice poorer fuel economy (your car uses more petrol)
The engine might hesitate or stutter when you accelerate
Your car might produce more visible exhaust smoke than usual
The check engine light will likely be illuminated on your dashboard
If you notice any of these symptoms, it’s a good idea to get your car checked with a proper car diagnostic test as soon as possible.
What Causes the P17D400 Fault Code in Audis?
Several issues can trigger this fault code in your Audi:
1. Carbon Build-up
The most common cause is carbon deposits building up on the EGR valve or in the passages. This happens naturally over time as part of normal driving.
2. Faulty EGR Valve
Sometimes the EGR valve itself wears out and doesn’t open or close properly when the car’s computer tells it to.
3. Electrical Problems
Wiring issues, damaged connectors, or problems with the sensors that monitor the EGR system can also trigger this code.
4. Vacuum Leaks
Some EGR systems use vacuum pressure to operate. Leaks in these lines can cause improper operation.
5. Control Module Issues
Occasionally, the problem isn’t with the EGR system at all but with the car’s computer that controls it.
Different Audi Models Affected by P17D400
The P17D400 Audi fault code can appear in many Audi models, but it’s more common in some than others:
Audi Model
Likelihood of P17D400 Fault Code
Common Model Years Affected
A3
High
2013-2020
A4
Medium
2009-2019
A6
Medium
2011-2018
Q5
High
2012-2020
Q7
Medium
2010-2019
TT
Low
2015-2020
How to Fix the P17D400 Audi Fault Code
Fixing this issue usually involves one or more of these steps:
1. EGR System Cleaning
Often, a thorough cleaning of the EGR valve and passages can resolve the issue. This removes carbon build-up that might be preventing proper operation.
2. EGR Valve Replacement
If the valve is damaged or too clogged to clean effectively, it will need to be replaced. Quality Audi repairs using genuine or high-quality parts are essential here.
3. Wiring Repairs
If electrical issues are causing the problem, your Audi specialist will need to repair or replace damaged wiring or connectors.
4. Control Module Updates
Sometimes, updating the software in your car’s computer can resolve the issue, particularly if it’s a known problem that Audi has released a fix for.
5. Related Component Checks
The technician should also check related components like oxygen sensors or other emissions equipment that might be contributing to the problem.
Why Professional Diagnosis is Important
While it might be tempting to clear the code and hope for the best, this rarely solves the underlying problem. The code will typically return, and meanwhile, your car might:
Use more fuel than necessary
Produce more pollution
Develop more serious and expensive problems if left untreated
At First Auto Centre, our car diagnostics equipment can pinpoint exactly what’s triggering the P17D400 code in your Audi, saving you time and money by focusing on the real issue.
Preventative Maintenance to Avoid P17D400
The best way to avoid dealing with this fault code is through regular maintenance:
Regular Servicing: Scheduling routine car servicing helps catch issues before they become serious problems.
Fuel Quality: Using high-quality fuel can help reduce carbon build-up in your engine.
Driving Habits: Allowing your car to warm up properly and avoiding too many short trips can help prevent EGR issues.
Cleaning Products: Occasionally using fuel system cleaners recommended for Audis might help keep your EGR system cleaner.
Listen to Your Car: If you notice any changes in how your car runs, getting it checked early can prevent more serious issues from developing.
The Cost of Fixing P17D400 in Audis
The cost to fix this issue can vary depending on what’s causing it:
Repair Type
Approximate Cost Range
Time Required
EGR Cleaning
£80-£150
1-2 hours
EGR Valve Replacement
£200-£450
1-3 hours
Wiring Repairs
£100-£300
Varies
Software Updates
£80-£150
1 hour
Complete System Diagnosis
£60-£120
1-2 hours
These costs are estimates and can vary based on your specific Audi model and the extent of the problem. At First Auto Centre, we always provide clear quotes before beginning any work.
Why Choose an Audi Specialist for P17D400 Fault Code
Audis are sophisticated vehicles with complex computer systems. General mechanics might not have:
The specific diagnostic equipment needed for Audi fault codes
Access to Audi technical bulletins and updates
Experience with the common issues affecting different Audi models
Training on Audi-specific systems and components
As an Audi specialist in London, First Auto Centre has invested in the tools, training, and expertise needed to properly diagnose and fix issues like the P17D400 Audi fault code. Our Audi specialist technicians are trained to quickly identify and resolve these specific fault codes, saving you time and money.
Frequently Asked Questions About the P17D400 Audi Fault Code
Can I still drive my Audi if it shows the P17D400 fault code?
While your car will likely still run, it’s not recommended to drive it for extended periods with the P17D400 fault code present. You might experience reduced performance, poor fuel economy, and could potentially cause more damage to your vehicle’s emissions system. It’s best to have it checked by a qualified Audi specialist as soon as possible.
Will the P17D400 fault code clear itself?
Generally, no. Even if the check engine light temporarily goes off, without fixing the underlying issue, the P17D400 fault code will likely return. Proper Audi diagnostics performed by an experienced Audi specialist and appropriate repairs are needed to permanently resolve the issue.
How urgent is it to fix a P17D400 Audi fault code?
While it’s not usually an emergency that requires immediate roadside assistance, you should plan to have the P17D400 fault code looked at within a few weeks of it appearing. Continuing to drive with EGR system problems can lead to decreased fuel efficiency and potentially more serious engine issues over time. A professional Audi specialist can properly diagnose the severity of your specific situation.
Can I fix the P17D400 code myself?
Unless you have experience with automotive repairs and the proper diagnostic equipment, this isn’t typically a DIY job. EGR systems can be complicated to access and clean properly, and incorrect repairs might cause more problems. Professional Audi servicing is recommended for these types of issues.
Will this fault affect my MOT test?
Yes, it potentially could. Since the fault relates to your emissions system, your vehicle might produce higher emissions levels than allowed, which could cause an MOT failure. The UK government’s guide to MOT testing explains that emissions are a critical part of the test, and problems with systems like the EGR can lead to failure. Getting this fixed before your MOT test is a good idea.
How long does it take to fix a P17D400 code?
The repair time depends on the underlying cause, but most EGR-related repairs can be completed in a few hours. At First Auto Centre, we’ll give you an estimated completion time when you bring your vehicle in.
Conclusion
The P17D400 Audi fault code is typically related to the EGR system and, while not usually an emergency, should be addressed promptly to keep your vehicle running efficiently and cleanly.
If your Audi is showing this P17D400 fault code or you’re experiencing symptoms that might be related, contact us at First Auto Centre. As trusted Audi specialist technicians in London, we have the expertise and equipment to diagnose and fix your car’s issues quickly and efficiently.
Remember that regular car servicing is the best way to prevent these kinds of issues from developing in the first place. Don’t wait until there’s a problem – preventative maintenance saves you money and hassle in the long run!
