Lets you sell without buying a second smog check, when a valid certificate already went to the DMV at renewal within the last 90 days. You certify you have not touched the emission system; the buyer signs to acknowledge they are taking the car on that basis.
Written against REG 139 (Rev 5/2007), issued under California Vehicle Code 5751.5.
That last rule is the one to be certain about before you sign. A REG 139 on a car you suspect would fail can turn into an obligation to repair it at your own cost.
Two documents, and they are not the same thing. Take the blank REG 139 from the dmv.ca.gov copy so you get the revision that is current today, then print our REG 139 guide and keep it beside you while you fill theirs in.
This is the actual REG 139, rendered from the PDF the California Department of Motor Vehicles publishes and completed end to end: letterhead, every field, and the blocks at the foot.
Amber — you write it
Grey — not yours to fill
Numbered — explained below
The actual REG 139. The seller signs twice - once under the certification that the emission system has not been modified, once under the warning to the buyer - and the buyer signs to acknowledge no second smog certificate is coming. Read the buyer's rights above that line before you sign it.
Field by field
Every line, in the order you meet it
1
You fill this in
Make, VIN and licence plate number
Three items identifying the car, and the only vehicle detail on the form.
Watch out: This form only works where a valid smog certificate went to the DMV with a registration renewal in the last 90 days - not one bought for the sale.
2
You fill this in
Seller's certification
Print your name, sign, and date under the statement about the emission system.
Watch out: You are certifying you have not modified, and know of nobody who has modified, the emission system in a way that would fail the test required by Health and Safety Code 44015. After an exhaust or engine-management change, do not sign this.
3
You fill this in
Seller again, under the warning to the buyer
The same name, signature and date a second time, below the warning block.
Watch out: Both signatures are needed. The second one sits under the paragraph that tells the buyer what they are giving up, which is why it is separate.
4
The buyer fills this in
Buyer's acknowledgement
The buyer prints their name, signs and dates to acknowledge no additional smog certificate is coming.
Watch out: Read what the buyer keeps before you hand this over: they may have the car tested first, and if it fails you owe them the cost of the test and the repairs to bring it up to standard before the sale completes.
At a glance
What goes where
On the form
What to put in it
Make, VIN, licence plate number
Three items identifying the car. Nothing else about the vehicle appears on the form.
The seller's certification
Pre-printed, and worth reading before signing: that you have not modified, and have no knowledge of anyone else modifying, the emission system in any way that would make it fail the tests required by Health and Safety Code section 44015. Under penalty of perjury.
Printed name and signature of seller
Twice - once under the certification, once under the warning to the buyer.
Printed name and signature of buyer
The buyer signs to acknowledge that the seller is not required to provide an additional smog certificate for this transaction.
What gets this one rejected
•Using it where the certificate was obtained specifically for the transfer. This form is only for a certificate submitted with a registration renewal that has not been used up.
•Using it outside the 90-day validity window. Past 90 days the exemption is gone and a fresh smog check is on you.
•Signing it after changing the exhaust, the catalytic converter or the engine management. That is exactly what the perjury declaration is aimed at.
•Handing it over without the buyer's signature. The buyer's acknowledgement is the half that protects you.
Rules that decide whether it is accepted
•['What the buyer is entitled to do', 'The form spells it out: the buyer may have the vehicle tested at a licensed smog check station before the sale completes. If it passes, they pay for the test. If it fails, you must reimburse them the cost of the test and, without expense to them, have the vehicle repaired to meet emission standards before the sale completes.']
Every line here was read off REG 139 (Rev 5/2007) itself —
the PDF is here — and off the California Department of Motor Vehicles pages.
This is plain-language help with a form, not legal advice, and where our wording and the agency's differ,
theirs governs.
