Rick's Free Auto Repair Advice

Drive Cycle

What is a drive cycle?

Simply put, a drive cycle is a set of testing conditions for a certain portion of a car’s emission system. In order to set the car’s OBDII readiness monitors to READY, the vehicle must complete a drive cycle. Every carmaker has established their own drive cycle and it’s unique to the year, make, model, and engine. So you can’t use one car maker’s drive cycle on any other vehicle.

NOTE: Some drive cycles must begin with a cold start. There’s a set definition for “cold start.” See this post for more information on cold start.

Here’s a Ford 2014 Catalytic Converter drive cycle example

In order to test for a P0420 or P0430 catalyst efficiency the following conditions must be met:

• Computer has tested the oxygen sensor response time and the sensors have all passed
• Codes P0133/P0153 must NOT be stored in the computer
• The secondary air pump must not be stuck in the ON position and codes P0412/P1414 must not be set
• No evaporative emissions codes are set— No P0442/P0456
• No EGR stuck open codes are set — No P0402
• The following sensors must be operational ECT, IAT, TP, VSS, CKP, and MAF
• No misfire or ignition coil codes set
• No fuel monitor codes set
• No electronic throttle body codes set
• Time since start must be greater than 330-seconds (from a 70°F startup temp
• Time since the computer went into closed loop must be at least 30-seconds
• Engine coolant must be at least 170°F
• Intake air temp must be at least 20°F
• Rear O2 sensor inferred temp must be at least 900°F
• EGR flow must be at least 1%, but no more than 12%
• Throttle position must be part throttle
• Vehicle speed must be greater than 5-mph but not greater than 70-mph
• Fuel level must be at least 15%
• First Air Mass Cell must be 1.0-lb/min and no more than 2.0-lb/min
• Front O2 sensor must switch at least 50 times
• Second Air Mass Cell must be 2.0-lb/min and no more than 3.0-lb/min
• Front O2 sensor must switch at least 70 times
• Third Air Mass Cell must be 3.0-lb/min and no more than 4.0-lb/min
• Rear O2 sensor rich since last monitor attempt 0.45 volts
• Rear O2 sensor lean with injectors off (voltage needed to enter monitor) 0.1 volts
•Rear O2 sensor reads rich after fuel turned back on (voltage needed to complete monitor) 0.45 volts

Once all the criteria have been met and all the reading come back within spec, the computer will turn the catalytic converter readiness monitor to READY/PASS

For more information on readiness monitors and drive cycles, see these posts

Readiness Monitors and Drive Cycles

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