View Full Version : hi need procedure for checking head etc.

10-11-2010, 04:42 AM
Hi everyone, i have a 92 previa no alltrac,no sc. My idle is rough (all the time) and hesitates slightly before acceleration. I jumped the terminals and got codes 25 and 51. I have no idea what the 51 could be? The only thing i think it could be is the air bag light is always on. The 25 says o2 sensors and such (very broad). Now since i disconnected the battery, only the code 51 comes up. No doubt i have to drive it some more to get the 25 code to come up again. Thats a problem because it doesnt have a plate on it and my temp has to be used for a smog check. I need to fix my issues before i go that route. I cant take the chance of running out my temp plate with the van still in need of repair. So here are my thoughts.... i never did a compression check or checked to see if the head is cracked or a blown head gasket or whatever. Since this wouldve been a better place to start, can someone walk me through EXACTLY how to check if the head gasket is blown or if the head is cracked? I just ordered a new cat and o2 sensors but i highly doubt if these are the problem but maybe. i figure in the meantime while i am waiting for those to come in i could check for the head stuff, can you folks help? Sorry about the long email, Tom