Honda P0325, P1009

Fix Honda P0325, P1009

Shops are reporting a high incidence of Honda P0325, P1009 trouble codes. The Honda P1009 is an enhanced manufacturer specific code defined as: P1009 Variable Timing Control System Advance Malfunction – Automatic Transmission. Honda has issued a service bulletin #08-089 to address the P1009 issue on the vehicles listed below.

Honda P1009 vehicles affected by service bulletin #08-089

2005-08 CR-V
2009 CR-V 2WD VIN 5J6RE38..9L000001 through 5JRE38..9L000019, and 3CZRE38..9G70000a through 3CZRE38..9G700490, and JHLRE38..9C000001 through JHLRE38..9C997328
2009 CR-V 4WD VIN 5J6RE48..9L000001 through 5J6RE48..9L000025, and JHLRE48..9C000001 through JHLRE48..9C007328

Fix for Honda P1009

The service bulletin advises tech to updated the software in the above mentioned vehicles to correct the flaw in the software that misinterprets the VTC inputs and see the inputs as a fault in the VTC system.

Honda P0325 Knock sensor

P0325: Knock Sensor (KS) Circuit Malfunction

The knock sensor is a piezo ceramic element that generates electrical signals when it detects a vibration strong enough to represent knock in the cylinder. When the engine is running, the ECM expects to see a variation in the signal from the knock sensor. If the signal doesn’t vary during a set period of time, the ECM stores a P0325: Knock Sensor (KS) Circuit Malfunction trouble code and turns on the check engine light.

Diagnosing a Honda P0325

The ECM supplies a very low reference signal to the knock sensor on the red/blue wire. Start by checking for a reference voltage around 0.03 volts in the knock sensor connector with the knock sensor connector unplugged. If you don’t see that voltage, check the wiring harness and terminals from the ECM to the connector

Next, reconnect the knock sensor connector and back probe the sensor wire. Connect your scope and watch the pattern with the engine running at idle and again at 3000 to 4000 RPM. The voltage should be very low at idle; around +1 volt to -1 volt. If you don’t see those voltages, check the wiring harness condition. If the harness is good, replace the knock sensor.

The knock sensor is mounted on the cylinder block and detects engine knocking. The vibration caused by knocking is converted into electrical signals through the piezo ceramic element. The engine control module (ECM)/powertrain control module (PCM) controls the ignition timing based on the electrical signals. If the signal from the knock sensor does not vary for a set time period, the ECM/PCM detects a malfunction and stores a DTC.

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