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Ken Peterson
Premium Member
join:2000-12-08

Ken Peterson

Premium Member

'99 Camry 2.2 4 cyl - Code P0171

The "check engine" light came on with my '99 Camry 2.2 4 cyl. and Autozone's OBD-II code reader yielded a P0171. From what I've read, the MAF sensor may require replacement. There are a bunch of things that can throw this code, but this seems to be the fix for the majority of searches I've undertaken.

Some people speak of cleaning the MAF sensor. Is this worth trying? If so, I see some stores sell a MAF sensor cleaner, claiming that brake cleaner (or carb cleaner) is too aggressive.

Is an attempt to clean the MAF sensor one to try? I guess I have nothing to lose and everything to gain if it works, yes?

Any tips? As always, I'd be grateful for advice.

Cho Baka
MVM
join:2000-11-23
there

1 recommendation

Cho Baka

MVM

Cleaning it worked on my brother's car.

More details here:
»[Tech] P0171 Using a scantool

Ken Peterson
Premium Member
join:2000-12-08

Ken Peterson

Premium Member

Thank you for this post. It gives me hope. I think I have some TV tuner cleaner (back from the day of rotary tuners) kicking around which will probably do as good of a job as the cleaner in the link.

Cho Baka
MVM
join:2000-11-23
there

1 recommendation

Cho Baka

MVM

Just be careful that the solvent doesn't swell the o-ring, and that when you install it you don't pinch that o-ring.

Ken Peterson
Premium Member
join:2000-12-08

Ken Peterson

Premium Member

Click for full size
Click for full size
Click for full size
Click for full size
Interestingly I could not find what looked like a MAF sensor on my car. Please take a gander at the pics and see what you can identify. There is some sort of assembly with a chamber under the snorkel which I cannot ID (circled part). You can see another angle of that chamber/plenum in the pic above the one that has the red circle.

For what it's worth, I took out the air filter assembly all together, shook out the crap that was in it, disconnected the snorkel and the various vacuum hoses and electrical connectors, made sure they were on firmly (removed and replaced X3 or so) to make sure their was no oxidization, then put it all back together and disconnected the battery for a minute, then reconnected everything, started the car and the "check engine" light has gone off... for now. It may take some more cycles for it to re-appear, but until it does, I am tentatively happy.

Cho Baka
MVM
join:2000-11-23
there

Cho Baka to Ken Peterson

MVM

to Ken Peterson
Ah crap!
I was thinking of a different model year 4 cylinder Camry.

Yours has a MAP sensor instead of an airflow meter. Let me think a little and post back.

The circled one is an EVAP VSV.

Ken Peterson
Premium Member
join:2000-12-08

Ken Peterson

Premium Member

Click for full size
The MAP sensor is up on the firewall on the top picture, upper left. (faintly circled in red) I also checked it's electrical connection, but I did not test it. I removed and replaced the connector a few times to make sure it was getting a good connection.

I drove the car around today and the "check engine" light did not come on... so far, so good.

Cho Baka
MVM
join:2000-11-23
there

Cho Baka to Ken Peterson

MVM

to Ken Peterson
Are you experiencing any hesitation while accelerating?

Unfortunately, given that you have a MAP sensor, there is no single common thing to shoot for.

If I were working on the vehicle, the first thing I would do is to roadtest it, and then view the data from the O2 sensors.

Do you have any exhaust leaks?

Ken Peterson
Premium Member
join:2000-12-08

Ken Peterson

Premium Member

Since yesterday's endeavors, all seems well. The "check engine" light is off and the engine appears to be acting normally.

I'll keep an eye on it and let you know if anything turns up, and thank you for your efforts to help and support!

Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium Member
join:2001-04-19
1970 442 W30

1 edit

Doctor Olds to Ken Peterson

Premium Member

to Ken Peterson
(if you had one) Use MAF Sensor Cleaner for the best results so that you leave no unwanted residues.

DIYER25
@lausd.net

DIYER25 to Ken Peterson

Anon

to Ken Peterson
There it is... your MAF sensor. It's just to the lower left of the red circle. (on the air intake coming from your air filter box) be careful NOT TO TOUCH THE WIRES on the sensor they are tin and fragile. disconnect with care)

Cho Baka
MVM
join:2000-11-23
there

Cho Baka

MVM

Not sure what you see, but it isn't a MAF.

Ken Peterson
Premium Member
join:2000-12-08

1 recommendation

Ken Peterson

Premium Member

If you are referring to what I have circled in yellow, that's the Intake Air Temperature (IAT) sensor.