Help! Check Engine Light

[Guest]

On my 98LS (180,000 miles), I noticed a hesitation while slowing to enter a parking lot--thought the engine was cutting out; it did not die but the check engine light (CEL) came on. Then when leaving the lot an hour later I got a brief hesitation when trying to accelerate, and then a slight surge. Took it to my indy mechanic yesterday: code was "P0172 Rich" on the left bank pre-cat O2 sensor. Replaced for $245. Ouch. Mechanic: "Not sure that will be all but it is the first thing; drive it until the light comes back on." I drove it maybe 20 miles that night without CEL but this morning after flooring it to get into traffic there was more hesitation and the CEL was back on.

The mechanic made it sound like if the O2 sensor was not the culprit we (his work, my life savings!) would be replacing part after part to find what was causing the problem. In order of likelihood: fuel pump, pressure regulator, fuel filter, injectors, mass air flow meter, engine coolant sensor, plugs/wires, and lastly the home run: engine control module!

Is it time I break down and actually go to Lexus?

Any advice would be greatly appreciated!

[etex]

I'm still new to Lexus, so more talent is needed here. I remember reading, however, that the coils are often the last thing someone thinks of when trying to eliminate such problems.

Hopefully someone else will chime in.

[SRK]

Here's the deal. The O2 sensor reports a rich condition, so your mechanic replaces the sensor?!!!!!! How does he figure that?!!!!!

The sensor is reading the exhaust gas oxygen content. Something is reducing the O2 content, like excess fuel. So a leaky injector, or some such is doing it. The O2 sensor was doing it's job. He goes and throws it away. It was not the problem.

I don't know if you should go to Lexus - I would - but you need to find someone who knows what they are doing......

[Guest]

Here is a little more to the story if anyone can diagnose more from this.

This morning I backed the car out of the garage. No probelm, everything completely normal. Parked it in the drive for several hours, then went to start it to move it, and... chug chug, chug. Though I ws trying to start it just like I alway do, it seemed like it was flooded and would not start. After about 5 tries, I waited 5 minutes and tried again. Started right up just like normal but it did blow out quite a bit of white smoke--consistent with the flooding theory. The drive does have about a 20 degree incline and nose was down but I don't think that has anything to do with it. No check engine light came on, but I really didn't drive it, just parked it on the street in case I have to tow it. Oh, I also noticed that it idled at 900-950 rpm in park (Is that too fast?) but drops back to 600 in gear.

Any more ideas from these clues?? This seems to go along with the prior comment about too much gas in the system. But why would that be with it just being parked for several hours? It acted like it was floode from the very fist turn of the key.

[SKperformance]

I have a similar issue with bank 1 running rich.

I ran seafoam almost pure to clean tehm and still no change. It also has a hard start when cold but the car runs fine.

I replaced the timing belt and idlers and it has disappeared for now but i know it was not the problem i had.

I think mine if from an injector not working properly and staying open.

If it were a ignitor then the car would idle rough also.

[92Lex]

Check the ECT sensor.

[Guest]

Well, after much seraching of the site I followed the recommendation to try SeaFoam injector cleaner and that initially seemed to do the trick! But no. The CEL returned the next day. then tried cleaning the Mass airflow sensor. THat did the job, four days now and no more CEL. See my post on that.

[acflye]

Well, after much seraching of the site I followed the recommendation to try SeaFoam injector cleaner and that initially seemed to do the trick! But no. The CEL returned the next day. then tried cleaning the Mass airflow sensor. THat did the job, four days now and no more CEL. See my post on that.

how did you clean the mass flow sensor, or did you have to take it to a mechanic.....thanks

[Guest]

Know this is well past the question but just to document for others later...

Search my post entitled: Victory Over Code P0172 Rich! Cleaning Mass Airflow Sensor Worked

I posted some pictures and instructions of how I did that.

Well, after much seraching of the site I followed the recommendation to try SeaFoam injector cleaner and that initially seemed to do the trick! But no. The CEL returned the next day. then tried cleaning the Mass airflow sensor. THat did the job, four days now and no more CEL. See my post on that.

how did you clean the mass flow sensor, or did you have to take it to a mechanic.....thanks

[AHJGTA]

I also got the Engine icon. My mechanic showed me the o2 sensor readings on his reader and one of them was stuck at 0 Volts. Time for a change on at least that one. Now here's where it gets puzzling. The mechanic's part source quotes $200. Lexus quotes $350. and ebay quotes $30 for NGK. I already ordered off ebay.