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Volkswagen Passat code P1177

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Volkswagen Passat code P1177

Volkswagen Passat code P1177, will be today's challenge. A customer brought her Volkswagen Passat in today with a check engine light on. After scanning the Passat, we found code P1177. Now keep in mind, this code is just a starting point, it will only send us in the right direction. There will still be some diagnostics procedures that need to be performed before we can put or finger on the actual cause of the P1177 code being set. What this check engine light code tells us is: O2S Sensor Heater Circuit Short To Ground Bank 1 Sensor 2. Now, our task is to find out why this code was set. With that being said, lets get on with the tests:

Scan for diagnostic trouble codes

Customer Concern:

Code P1177, check engine light is on.


1. Check the O2 sensor before the three way catalytic converter, 11.5 volts minimum on the heater circuit.

2. Check the sensor signal, 0.40 to 0.50 volts key on engine off.

3. Check the O2 sensor on the outlet side to the catalytic converter with the same readings as above.

4. Check for intake air leaks, use smoke regulated to 5 PSI or spray check.

5. Check the exhaust system for leaks before the catalytic converter.

You will need a good scan tool or code reader

Potential Causes:

Leaking Exhaust Flex Pipe

Intake Air Leak

Heated Oxygen Sensor (HO2S) Bank 1 Sensor 1 Heater

Oxygen (O2) Sensor Bank 1 Sensor 1 Wiring

Oxygen (O2) Sensor Signal Circuit

Confirmed Fix:

Replaced Exhaust Flex Pipe

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This was our confirmed fix. if you have any questions or comments please feel free to post. I always want to hear from other serious techs


Gefforyt (author) on June 17, 2012:

To be completely honest with you, I dont have any idea what kinds of procedures or how much time was spent on your vehicle. But I have to say that 550 for some flex pipe and maybe an an hour and a half diagnostics, seems a little pricey to me. Next time you take your vehicle to a shop, do not tell them that you just came from a dealership. They will usually charge you for diagnostics anyway, so make them earn their money, which is why they are there.

Kay on May 25, 2012:

My '02 passat wagon was showing p1177 and my local vw dealership told me I needed to replace both catylitic converters which is big $$$. I took it to a shop and they figured out it was the flex pipe right before the catylitics. So $550 later the leak is gone and the check engine light has stayed off. My only question... Did I get ripped off at $550?

Mark on October 31, 2011:

I have a 2001 VW Passat, the check engine light and emissions workshop also coming on. Code P1177 is the code.. Help!!!

RayJ2046 on March 29, 2011:

Here's my post on another forum regarding P1176, and P1177. I'm revisiting this after a problem i fixed in the the other bank.

P1177 -- O2 correction behind catalyst B2 limit attained.

2 years ago i got the 1176 - same but other bank. On the lift my mechanic and i saw an exhaust leak and agreed that this was probably the problem. So i ok'd a replacement pipe w / cat, problem was solved.

I vow'd to go the "replace flex joint by muffler shop" route next time it happened to the other bank. So yesterday I took it to my the only muffler guy in town, Meinike, who told me it wouldn't solve my problem. He said, i could drill multiple holes into the pipe without triggering that code. He was so confident, and passed up an opportunity to make $ that now i wonder if it wasn't the cat in the first place?

So now thanks to this forum, i'm back to investigating the exhaust leak again. Why do i always see posts saying the job is around $100, and then my Meinike guy quotes me $350? any comments, please reply to thanks

Gdoke on March 12, 2011:

Took the V6 Passat to Cole Muffler, and for $80 they welded in a new flex pipe. the leak was fixed, and I cleared out the code. Weeks later, no return of the code.


Gdoke on January 31, 2011:

Good write up, I have same code and a loud exhaust leak. Once leak is repaired I'll post on whether the code is silenced.


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