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Error Code P045A is defined as Exhaust Gas Recirculation ‘B’ Control Circuit.
This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II, especially those made from 1996 up to the present day. These vehicles may include (but are not limited to) Vehicle brands may include (but are not limited to) Land Rover, GMC, Chevrolet, Dodge, Chrysler, Ford, Toyota, Honda, etc. Specifications on the definition, troubleshooting and repairs, of course, vary from one make and model to another.
The early EGR or Exhaust Gas Recirculation system components include the EGR valve, PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes), Engine Controlled Vacuum Switch or EGR Solenoid, and EGR Vacuum Modulator. Depending on the engine and the vehicle’s driving conditions, the PCM controls the EGR solenoid, which will operate the EGR vacuum modulator to regulate the opening and closing of the EGR valve.
Modern vehicles with EGR system use a step motor to control the flow rate of EGR from the exhaust manifold. This motor has four winding phases. It works depending on the output pulse signal of the PCM. Two windings are turned On and Off in sequence. Each time On pulse is sent, the will either open or closes, changing the flow rate. When there is no need for change in the flow rate, the PCM will not use the pulse signal. A certain voltage signal will be used to keep the valve at the particular opening.
The EGR is controlled by the vacuum solenoid. The solenoid is supplied with ignition voltage. The PCM controls the vacuum solenoid by grounding the control circuit (ground) or driver.
The main purpose of the driver is to supply ground for the object that is being controlled. Each driver has a specific fault that the PCM monitors. When the PCM turns a component on, the control circuit voltage is low or close to zero. When the component is turned off, the voltage on the control circuit is high, or near the battery voltage. The PCM looks out for these codes, and if doesn’t see the right voltage at the right, then the Error Code P045A is set.
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. Other than that, vehicles with this code usually don’t have drivability or performance issues.
Common causes for this code include:
- Defective EGR solenoid
- Defective EGR volume control solenoid valve
- Open or shorted (chaffing or damage) EGR volume control solenoid valve harness, causing excessive resistance in PCM
- Poor electrical connection in EGR volume control solenoid valve circuit
- Faulty EGR temperature sensor circuit
- Poor connection at the EGR solenoid harness (worn or loose pins)
- Water intrusion at the EGR solenoid harness
- Blockage in EGR control solenoid holding solenoid open or closed causing excessive resistance Loss of supply voltage to EGR solenoid
- Bad PCM
How to Check
Should you get this code, it is highly recommended that you refer to the vehicle’s specific repair guide for the specific year, make, and model of the engine.
With the ignition On and engine Off, use the scan tool to activate the EGR solenoid. Listen and take note for a clicking, as this indicates the solenoid is working.
How to Fix
If the solenoid works, the next thing you will have to check is the current draw on ground circuit. It should be less than 1 amp. If it is, then that means you have an intermittent problem. If not, then that means there’s an excessive resistance in the circuit, which means you should perform the following:
- If it’s activated, check whether you can blow lightly through it. If you CAN’T, that means there’s a blockage causing excessive resistance, and the EGR solenoid must be replaced.
- If there is NO blockage, then disconnect the EGR solenoid and the PCM connector that contains the EGR solenoid control circuit. Using DVOM (digital volt-ohm meter), check for resistance between the control circuit and battery ground. There should be infinite resistance. If there is not, then that means there’s a short to ground on control. Repair short to ground and retest as necessary.
- If the solenoid is not working properly (no clicking sound), then disconnect the EGR solenoid connector and connect a test light between two wires. Use the scan tool to command the EGR control solenoid on. The light should be activated. If it does, then replace the EGR solenoid. If it doesn’t, then you need to perform the following:
A – Check for 12V on the ignition supply voltage to the solenoid. If there is none, then check the supply circuit for open or short caused by chafing of breakage and retest.
B – If it still doesn’t work, then ground the EGR solenoid control circuit manually. The light should light up. If it does, then repair the EGR solenoid control circuit and retest as necessary. If it doesn’t, then you need to replace the EGR solenoid.
This entry only shows general information about the code. Make sure you also check the Technical Service Bulletins (TSB) that may apply to your vehicle.