Pete Quella

i HAVE REPLACED THE MAF, ECM, TPS, AIR IDLE CONTROL, THE BURN OFF RELAY AND THE MAF RELAY AND I STILL GET CODE 33 PLEASEHELP!

arbee

Since you seem to be replacing random parts in the hope you strike it lucky, try new fuel pump, injectors and maybe air conditioning compressor. If that doesn't do the trick, my only other suggestion would be to buy a FSM and use the diagnostic charts to find your problem.

Nomake Wan

Sorry you had to replace all those components unnecessarily. Code 33 is pretty much useless. Programming that error out via a chip will “solve” the problem.

If you want to try your hand at “fixing” it, then as arbee says, go buy a factory service manual. They’re about $20 on RockAuto (look under your year in the Literature section). But plenty have tried, failed, disabled the code, and kept on driving without further issue.

Best of luck.

Red86Z51

There were a lot of issues with the ECM causing erroneous Code 33s. I am attaching a write up I saved years ago which will give you some good insight into ECM caused 33 failures.

As for a factory service manual(s), go to ebay and find the correct GM manual(s) for your year car. Generic manuals purchased over the counter are just that, "generic", and will more than likely be a waste of money for diagnosing most problems. They are way to general.

Nomake Wan

The $20 FSM on RockAuto is the real GM Factory Service Manual. Far better deal than spending five times that for a greasy old book on eBay. Just a heads up.

Red86Z51

Roger that. I've never shopped their literature section, so I missed they have those. Ebay can still be your friend for the hard-copy version of the FSM if your patient Smoking deals come across from time to time. Another option is to post a WTB ad in the parts section. You never know who might be willing to give a forum member a good deal on some manuals they no longer need.

tequilaboy

Have you done anything to the car that could increase the airflow relative to the tps position or have you adjusted the tps? Aftermarket throttle body, increased displacement (383), heads/cam/intake, blower, driving in a mine/below sea level, whatever?

Here's a log which includes startup showing normal MAF flow in relation to the tps and rpm: https://datazap.me/u/elijah/gas-stat...-2619-2701-199

Note: The code 33 threshold is 45 gm/sec, so I've added some markers near the 45 gm/sec threshold for reference.

Some cars simply flow more air within the given rpm (<2000) and tps (1/4 throttle) constraints and may require threshold adjustment in the tune to avoid setting code 33.

Get an aldl cable or scan tool and scan it yourself for the answer. An open circuit on the maf signal wire will also cause a code 33 since the signal is pulled up by the ecm (10k pullup resistor).

Pete Quella

I solved it 2 bad mass air flow sensors back to back.

TommyFox

I have a used Bosch on the way. 3rd one.The aftermarket ones are all Chines junk..

Pete Quella

After 2 weeks of driving bliss code 33 showed back up on the way to work this morning, Another bad sensor?

arbee

You have two choices. Buy an FSM as you have been told to do and follow the diagnostic chart and DETERMINE the cause of the code OR you can pull out your wallet and start chucking more parts at it. Your call.

Nomake Wan

Hi there.