DIY Answers. This section is for the staff of HAF to post detailed DIYs in response to the requests by the members.

OBD-2 Readyness Codes

Old 09-30-2009, 10:41 AM
JimBlake's Avatar
Super Moderator
Thread Starter
Join Date: May 2006
Location: Wisconsin
Posts: 17,422
Post OBD-2 Readyness Codes

Starting in 1996 all cars (in USA) have to conform to US-EPA rules called OBD-2. For convenience Hondas follow this in many other countries as well.

Part of the OBD-2 rules says the emmission-control system must perform certain tests on itself, to verify it's working OK. These are called "readyness" codes and they must be set OK before your car will pass an OBD-2 smog check.

If the readyness codes are not set, that does NOT cause the check-engine light. I just means the system hasn't finished testing itself. One big reason for this is to prevent a car from going through the test immediately after the ECU has been reset.

I'll start out this thread; from the Helm shop manual for 2003-2006 Accord 4-cyl. Anyone with a Helm book for other years can post up what they learn.

How to Set OBD-2 Readyness Codes for 2003-2006 Accord 4-cylinder:

Catalytic Converter:
ECT coolant temperature above 158F (70C)
IAT air temperature above -13F (-25C)
VSS road speed above 3mph (4.8km/hr)
Drive some stop & go, and some constant cruising, about 5 miles.

EVAP system:
Battery voltage above 10.5v
Engine to be left Idling.
ECT coolant temperature between 176F to 212F (80-100C)
MAP pressure less than 6.75psia (46.6kPa)
= (manifold vacuum at least 7.95psi or 55kPa)
VSS speed = zero
IAT temperature between 32F to 212F (0-100C)

A/F sensor (primary O2 sensor):
ECT coolant temperature above 158F (70C)
Drive including some steady cruising 50-62mph (80-100km/hr) for 10 seconds.
Drive including closed-throttle engine-braking for 5 seconds.

A/F sensor Heater:
Start & Idle for at least 1 minute

Misfire detection:
Always available
Always monitoring
This one pauses & resets when driving on rough road

Fuel system monitor:
Always available
Always monitoring (during closed-loop operation)
Pauses when Cat, EVAP, & A/F monitors activate

Always available
Always monitoring

EGR monitor:
ECT coolant temperature above 176F (80C)
Drive steady (4th or D) above 50mph (80km/hr) for 10 seconds.
Engine braking (closed throttle) from above 62mph (100km/hr) for 5 seconds.
Make sure OBD-2 error code P0401 is NOT showing.

Last edited by JimBlake; 09-30-2009 at 10:58 AM.
Old 10-07-2009, 08:17 AM
hondadude's Avatar
Super Moderator
Join Date: Aug 2006
Location: Fayetteville, AR
Posts: 2,170

Emission codes require a 2 trip "engine cycle" to set a CEL.
But will show a "Not Ready" on the first trip.
Old 04-20-2010, 10:22 AM
Join Date: Apr 2010
Posts: 5
Default Thanks!

The engine light turned off yesterday during my second trip of the day. Thank you all for all the help.
Related Topics
Thread Starter
Last Post
General Tech Help
07-06-2012 07:14 PM
General Tech Help
10-05-2009 09:53 AM
General Tech Help
10-04-2009 08:54 PM
General Tech Help
08-28-2007 02:55 PM
Do-It-Yourself Section
04-18-2006 03:44 AM

Thread Tools
Search this Thread
Quick Reply: OBD-2 Readyness Codes


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.