2000 Audi TT OBDC code P1136
My Audi TT is now 12 years old. I’m it’s second owner – and I’ve driven it for nearly 7 years now. It’s a classic German designed vehicle, with italian electronics (lambourgini), a modified Porche frame, and assembled in Hungary. The only thing designed by Audi other than the body shell is the 1.8T engine itself – which was used in most of VW’s entire fleet before going to a 2.0 T model in 2005.
I was driving out to the hills in the pre-dawn Sunday morning, hoping to catch the rising sun in Austin above the Pennbacker Bridge without any clouds. Along the way, while cruising at 70mph my little Audi TT lost almost total power and most of the lights on the driver’s display illumninated. “Oh Crap!” I said out loud while turning off the radio. I thought the timing belt had broken – as the engine had no power at all. I turned on my emergency blinkers and pulled over to the shoulder and stopped. It was then that I noticed that the car was still running, at a normal IDLE. “Okay, at least it’s not a timing belt” and I sat there and pondered what was happening. It was very early – the sun wasn’t even close to coming up. I called the house phone. The wife didn’t answer. I called her cell phone. The wife didn’t answer. I contemplated calling my parents who lived further away and considered my situation. The car was running, but I couldn’t go anwhere because when I gave it a little gas it ran super rough. The EPC light was on, the wheel tracking light was on, the engine check light was on – and I thought to myself “well, I guess it doesn’t matter.” as I contemplated whether to turn off the car. It wasn’t like I was going to go anywhere. I turned off the car.
I took a breath and turned the key. The car started – all lights reset except the check engine light. The car seemed to respond to gas. I had to make a decision. Do I go forward into the hills that it was a fluke or turn-around and go home. I was 75% of the way to the Pennybacker Bridge, so I said, “Screw it!” and pulled out and headed to the bridge.
About 1/4 of a mile away from the bridge, fate intervened. The car was back into limp mode, the EPC light and the wheel slip light was back on, and the check engine light was now a constant companion. I coasted to the bridge and pulled into the shoulder and parked. At least I wouldn’t get a ticket if asked – because I had to pull over for an actual emergency. “Well, at least I can take some pictures and waste some time and maybe the wife will be awake if I have to call her again.”
I took out my camera, tripod, remote release cable and headed up the hill. I shot a few different angles – but my time spent on the side of the road earlier prevented my capturing the golden yellow of the rising sun. After I took the shots that I wanted, I walked back down the hill and put the camera into the car.
I made it home okay and only experienced one more limp mode.
Later that day, I hooked up the OBDC reader and found code P1136. “Lean Mixture, Right Bank” This code indicated that my Mass Air Flow (MAF) sensor was bad, or that I had a vacuum leak.
I took apart the top end of the engine and took out the MAF and looked at it. The price range for a new MAF unit is about $70-$125. Or, I could disassemble the MAF with a T20 security torque socket (the one with a nipple in the middle) and clean the MAF with isopropyl alcohol.
I had to order the part but it wouldn’t be available until the next day. I decided to put the car back together and then do it once again after I got the part in my hand.
And then – the “A-ha!” moment happened.
There is a brake vacuum hose that is connected to the intake manifold on the front of the car and routes under the MAF assembly to the engine firewall, before heading into the car. The material for this vacuum hose isn’t rubber. It’s like a hard plastic rubber – perhaps it was that way because of age. Anyhow, at the middle is a one way valve for the vacuum to keep the line clear and avoid the ingestion of air into the intake manifold from the brake system.
Yes, the hard plastic hose was fractured on both sides of the valve. The use of some silicone tape (stretch and seal) was used against the valve, and a clamp to make sure it wouldn’t come loose or leak. I assembled the car back together. I hooked the OBDC to the car and cleared the code and restarted the car.
Fixed. Yay. That was the cheapest fix (although somewhat frustrating) that I could have imagined.
I made a mental note of my mileage, looked at the other hoses in the engine compartment and have decided to get the timing belt replaced before 140k miles (it was last replaced at 80k miles).
Now… do I trust my little 1.8T engine to take me places. Yes, it’s a reliable car. You just have to maintain it.
Why did this happen to me? Well, I had my car inspected last month, but previous to the inspection I had my oil changed and a new air filter installed. I believe the vacuum hose must have fractured when the oil tech who replaced the air filter shut the asembly down on top of the brake vacuum line.
I think when I have my timing belt changed – a good preventive measure will be to ask that all of the hoses in the engine compartment be replaced if possible.
I plan on keeping my car until the wheels fall off.
So, if you see this little car heading down the road in the Texas Hill Country, it’s most likely me looking for perspective and a place to take some pictures.
Hopefully, you won’t see me on the side of the road with my emegency blinkers on.