The good old service engine light came on last week. The code was p1171 (bank 1 sensor 1). So I installed a new bosch 02 sensor, cleared the codes and went on my way. Yesterday the Service Engine light came on again. This time with the following codes: P0171, P0130, P1171, P1412, and P0155. Some of these codes are the same as before I changed the sensor. Bank 1 sensor 1 is the driver side pre-cat, correct? This is my daily driver so I have continued to drive it with the light on. I can smell the unburnt gasoline when I'm at idle. My mileage has gone down hill fast. Any ideas on a fix would be appreciated.

 

you losing any coolant? have you done the headgaskets yet? Have you pulled and looked at any of the spark plugs?

 

I'm not losing any coolant that I have noticed. Never a drip or a puddle in the drive. I would notice that. The plugs and wires were changed around 1000 miles ago. I went with the bosch +4s and the 8.5 wires. If there was a problem there wouldn't I get a misfire. I have not changed the head gaskets. The tip of the exhaust is covered with thick soot. I have to clean it every night. I can clear the codes and it is fine till I either turn on the air, or drive over 35mph. I'll check the plugs over my lunch hour.

 

Could the SAI control valve, or a vacuum leak cause any of the codes?

 

are you running a paper filter or K&N filter? when was the last time it was changed? your codes are leaning towards an MAF problem but i would check the plugs and filters first.

 

You can try this too and see if it's a temp fix,

http://www.amazon.com/CRC-05110-Mass.../dp/B000J19XSA

If it is and the problems come back, might be time for a new MAF sensor.
________
VALIANT

 

NO. you can't use cleaner on a D2 MAF. It will kill it for sure.

 

I have a paper filter. I'm sure it needs changed. Now that this subject has come up, The silver tube that is on the bottom of the air intake box where the filter is located has a large hole in the side of it. Am I just hurting my milage with that or can that cause a real problem? The manual refers to an air filter for the SAI system. Is there another air filter some where? Thanks everyone for the ideas. I'll post results, good or bad, when this is resolved.

 

There is a foam filter on the SAI pump and from RAVE:

 

Hi Big

Did you get this issue fixed? I had a very similar issue just recently (although note that I don't have the SAI).

With mine, Service Engine Soon light came on, slightly rough idle, and I could smell un-burnt gas. The code indicated Bank 1 Sensor 1 (drivers side, pre cat), so I replaced the O2 sensor with a Bosch sensor. Then I got several other various codes relating to the O2 sensor and mixture; most of them were for Bank 1 Sensor 1 and lean mixture, but I also got P0155 which I believe is Bank 2 Sensor 1...

At first I was going to chase the spark plugs and wires (actually bought them, just haven't put them on yet), but someone said I should check the O2 sensor connector AND replace the OTHER front O2 sensor (Bank 2 Sensor 1)...

They said if you have significant miles (60,000) then you should ALWAYS replace O2 sensors in pairs (either both front, or both back). I didn't think this was really the problem, but I figured the other O2 Sensor had some miles on it, so I replaced the other front sensor (Bank 2 Sensor 1), cleared the codes and everything is now good and I haven't had any more codes! Idles smooth!

I am not a mechanic, nor an export, but I am now a believer that O2 sensors should be replaced in pairs. I hate to suggest you simply throw parts at this, but if I were in your shoes, I would replace the other front O2 sensor (if you haven't already) and see what happens. If you have 72K miles on the other sensor, it will be time soon anyway...

Hope this helps, just thought it was similar to my experience...

Good luck.

Lee
2000 Discovery
85,000 miles