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Joined: Nov 2013
Posts: 8
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2004 Toyota Celica GTS Tsunami

Joined: Nov 2013
Posts: 8
Dec 7, 11:10am - #449744 
Intermittent OBD error code 171 (System too lean) - 04 GTS

Hi, I have been picking up this intermittent OBD error code 171 (System too lean) on my 04 GTS the past few months. Check Engine Light comes on for awhile then goes off. In addition, there is also an slight odour of exhaust fumes or something in the cabin when driving more than 30 miles. Performance seems good as well as idle, here's what I've done:

Cleaned MAF
Cleaned the throttle body and IAC valve
Replaced Air Filter
Replaced PCV valve
Visually inspected vacuum hoses I could without taking anything apart
Reset the ECU, but the CEL came back shortly afterwards (300 miles)
Replaced Spark Plugs (running almost white. Grey = too lean)
Used sea foam in the gas
Running only Premium gas
No excessive oil burning or loss, average

I have spent a lot of time reviewing the forms on this on several sites and am thinking O2 Senor(s), Cat, Exhaust leak, Intake manifold leak or dirty fuel filter or faulty injectors?

Have it scheduled to go to the Toyota Dealer next week and am not looking forward to it.

Comments welcome, thanks.

1970 Celica GT - 275,000 miles - retired
1980 Celica GT - 350,000 miles - retired
2003 Celica GT - 171,000 km's - Being Sold
2004 Celica GTS Tsunami - 151,000 km's - driving
Joined: Mar 2015
Posts: 3
New Member
New Member

Joined: Mar 2015
Posts: 3
Mar 23, 4:39am - #450535 
I am having the same problem on my 02 GT. The only thing I haven't done is clean the throttle body. Never have time to do it(always working). I just replaced the o2 sensor, reset the ECU, and light came back on after driving 15-20 miles. I went to a local mechanic shop about 3 times this week, and nothing. I guess I'll have to do the same thing you are doing.

Joined: Mar 2015
Posts: 2
New Member
2000 Silver Toyota Celica GT
New Member
2000 Toyota Celica GT

Joined: Mar 2015
Posts: 2
Victoria, Canada
Mar 29, 3:25pm - #450544 
Do you have an aftermarket Intake like a CAI or SRI?

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2001 Toyota Celica GT

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