UltraGauge Screens
Check Engine/Readiness
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Readiness
Check Engine/Readiness
Check Engine
Readiness
The Vehicle’s Engine Control Unit (ECU) performs two types of tests on the vehicle’s emission system. The first type is a
continual test or real-time test in which the ECU continually monitors the state of various system sensors to determine if the
system is operating normally or if the system is outside of design specifications. For example, during normal operation should
the coolant temperature suddenly output the lowest or highest possible value, the system assumes a temperature sensor fault has
occurred. Typically the ECU then lights the “Check Engine Light” and posts a trouble code.
The second type of test is a non-continuous test and often referred to as a “monitor”. This type of test is a long term test carried
out during a “driving cycle”. Where the “driving cycle” might constitute the following:
Example driving cycle
1
1
.
.
A cold start
2
2
.
.
A certain amount of idle time
3
3
.
.
A certain level of acceleration (say 50%)
4
4
.
.
Maintain a highway speed for a given time (55MPH for 3 minutes)
5
5
.
.
Deceleration for a given time
6
6
.
.
A higher level of acceleration (say 80%)
7
7
.
.
Again hold a steady speed
8
8
.
.
Decelerate
The above is just an example, and each manufacturer will likely have a different “driving cycle”. Normally, the ECU will check
off each of the driving cycle stages as they happen and they may or may not be in a particular order. Ultimately it’s best to
search the web to determine if the driving cycle for your vehicle is known.
During the “driving cycle” several readiness tests may be performed. The tests performed are manufacturer dependent.
READINESS STATUS
Status indicates if a test has completed or not. If not completed (Not Ready), it can mean a system component has prevented
the test from completing. For example, if the Speed sensor is not working, the test cannot complete since the drive cycle
cannot be determined. However, it does not mean that the results of the test failed, only that the test completed or not.
Once a test completes, and the test is marked “Ready”, the test may have passed or failed. If the test failed there will likely
be trouble codes posted. Note that UltraGauge is simply the messenger, relaying information from the vehicle’s ECU, and
has no influence or impact upon the tests.
The Test Status displayed by UltraGauge is one of four values:
Status
Description
RDY
Ready. The test has been completed
NO
Not Ready. The test has not completed
N/A
The vehicle does not support the test.
NR
No Response– The vehicle did not respond because the ignition was not in the RUN position, or the vehicle does
not support “Current Drive Cycle” readiness. Or the ignition was switch OFF, then back ON while viewing
Readiness Status, and the vehicle is using 9141 or KWP2000 Protocol
UltraGauge Status Display
Status this current driving cycle
(Left Column Status)
Status since Trouble Codes last cleared
(Right Column Status)
The left column represents the readiness status for the
current driving
cycle
.
Each time the engine is started, and in some cases when the ignition is
switched off, the ECU attempts to rerun the various readiness
monitors/tests. If a test completes, it will be reflected in the left column
and the right column. If a monitor/test does not complete, “NO” will
The Right column represents the readiness status since the
trouble codes were last cleared. The right column is sticky, in
that once a test completes and the status changes from NOT
READY to READY, its sticks and will not revert back to
NOT READY unless the trouble codes are again cleared, even
if there are no trouble codes.
