It’s a good idea to test a suspect knock
sensor before you rush out and buy a new one. Before getting started, however, you’ll
want to have the vehicle’s repair information handy. Step 1. Check For Diagnostic Trouble errors Codes
- DTCs. The first thing you’ll want to do is check
for errors that could narrow down the troubleshooting process. Cars built after 1996 with on-board diagnostics
OBD 2 will usually set a code when there’s an issue with the knock sensor or its circuit. Some older cars wi
th OBD 1 will also store
a errors code when there’s a problem with the knock sensor. Faulty parts like bad spark plugs can cause
a knock sensor code, so you’ll need to inspect your vehicle thoroughly if it sets a DTC. You can check for diagnostic trouble codes
using a scan tool or code reader. These days, you can even get an inexpensive
OBD II code reader for your smartphone. Common Fault Codes: P0325
P0326 P0327
P0328 P0329
P0330 P0331
P0332 P0333
P0334 It’s important to point out, however, tha
t
DTCs do not tell you the exact problem with the car. Codes merely serve as a starting point for
further diagnostics. Step 2. Perform a Visual Inspection. Next, you can move on to performing a visual
inspection. You’ll want to look for issues, such as
damaged wires and poor connections. Make sure that the knock sensor’s electrical
connector is clean and tight. Repair any issues found during the visual
inspection, clear the DTCs, and see whether the problem returns. Step 3. Before removing a kno
ck sensor, ensure that
the ignition is turned off. Firstly, check the resistance of the sensor
using a multimeter; you can do this by connecting it to the sensor’s connectors. The resistance should be between 2,000 and
3,000 ohm. If this is not the case the sensor is probably
faulty. If the correct resistance is present, check
the electrical connectors associated to the knock sensor. If no voltage is present check all wiring
to ensure that there is no damage to the circuitry. Step 4. Test the Kn
ock Sensor Directly. Testing a knock sensor can be tricky. There are two primary types of knock sensors:
wideband piezoelectric and resonance piezoelectric. In the past, when wideband piezoelectric sensors
were more common, a popular test method was to tap on the engine near the knock sensor. If the sensor responded to the vibrations,
you knew it was working to some degree. But that test does not work on the newer,
resonance-style sensors. Most professionals test these sensors using
an alternate
method, which involves forcing the engine to ping while monitoring the sensor’s
output signal. Thanks for your attention and please subscribe
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