Originally Posted by ehudson

2 digit codes are usually from checking light flashes. Your code 67 is the same as a P0420 read with a scanner. It means "Catalyst system efficiency below threshold" This can sometimes be caused by a bad Catalytic converter or a problem with the O2 sensor located after the catalyst.

I found this list of codes elsewhere on the web. Maybe it will help...

__________________________________________________ ______________
For those of us who won't(can't) spend $$$ in OBD-ii scanners; there is an alternative to find out
about codes and that CHECK ENGINE light that is driving us crazy:
1) Go to Autozone and have them read your codes (it's free)
or
2) See the instructions below

WARNING!!!: USE AT YOUR OWN RISK.

HOW TO OBTAIN TROUBLE CODES MANUALLY (6Th Gen Accord - V6 & I4)
1) Find the Data Link Connector (DLC) located under the instrument panel in the driver's side.
2) Jump terminals 8 and 13 by connecting them with a wire/cable.

...............________
...._____|________|_____
.../|1...2...3...4...5...6...7...8|
../.|================ |.
./..|9.10.11.12.13.14.15.16|..
/------------------------------------
DATA LINK CONNECTOR (DLC)

3) Turn the ignition key to ON and observe the "CHECK ENGINE" light. It will flash the trouble codes. For example: 2
long flashes, pause and then 3 short flashes = 23 = P0325 = Knock sensor circuit fault.
One short flash = 1. One long flash = 10. If there is no trouble codes, the light will not flash.

Flashes.....Code(s)............................... ..........Description
1...............P0131,P0132....................... .........Primary heated O2 sensor circuit low/high voltage
3...............P0107,P0108....................... .........Manifold Absolute Pressure (MAP) sensor circuit low/high voltage
4.............. P0335,P0336.................................Cranks haft position sensor
5.............. P1128,P1129.................................Map sensor circuit low/high voltage
6...............P0117,P0118....................... .........Electronic Coolant Temperature (ECT) sensor circuit low/high input
7...............P0122,P0123,P1121,P1122........... Throttle position sensor (TPS) circuit low/high input
8...............P1359,P1361,P1362................. ....CKP/TDC sensor 1
9...............P1381,P1382....................... .........CYP Sensor
10.............P0112,P0113........................ ........Intake Air Temperature (IAT) sensor circuit low/high input
12.............P1491,P1498........................ ........EGR valve
13.............P1106,P1107,P1108.................. ...Barometric pressure sensor
14.............P0505,P1519........................ .........IAC valve
17.............P0500.............................. ..............VSS fault
20.............P1297,P1298........................ .........Electric Load Detector (ELD)
21.............P1253.............................. ..............VTEC
22.............P1257,P1258,P1259.................. ....VTEC
23.............P0325.............................. ..............Knock sensor
41.............P0135,P1166,P1167.................. ....Primary heated O2 sensor
45.............P0171,P0172........................ .........System adaptive fuel too lean/rich
48.............P1162.............................. ..............Primary heated O2 sensor
58.............P1366,P1367........................ .........TDC sensor 2
61.............P0133,P1149,P1163,64,65............ Primary heated O2 sensor
63.............P0137,38,39........................ ...........Secondary heated O2 sensor
65.............P0141.............................. ...............Secondary heated O2 sensor
67.............P0420.............................. ...............Catalyst system efficiency below threshold
70.............P0715,20,25,30,40,53,58,63......... .Automatic transaxle malfunction
71.............P0300,P0301........................ ..........Random/Cylinder 1 misfire
72.............P0302.............................. ...............Cylinder 2 misfire
73.............P0303.............................. ...............Cylinder 3 misfire
74.............P0304.............................. ...............Cylinder 4 misfire
75.............P0305.............................. ...............Cylinder 5 misfire
76.............P0306.............................. ...............Cylinder 6 misfire
80.............P0401.............................. ...............EGR insufficient flow
86.............P0116.............................. ...............Electronic Coolant Temperature (ECT) sensor range/performance
90.............P1453,P1457........................ ..........EVAP control system leak
91.............P0452,P0453........................ ..........EVAP fuel tank pressure sensor low/high input

The codes that will not flash are as follows (will need code scanner):
P1607-PCM internal circuit failure and
P1705,06,38,39,53,68,73,91-Automatic transaxle failure

HOW TO CLEAR TROUBLE CODES (after fixing problem)
1) Remove ignition key (OFF)
2) Locate fuse panel on passenger's side (open door)
2) Remove fuse no. 13 (7.5 amp) for 10 seconds, and then place it back in.

I hope this info helps you, as much as it helped me.
Enjoy!