Why is there no signal from the crankshaft position sensor in the B12 engine?
3 Answers
It might be an issue with the sensor. It is recommended to have it checked at a 4S shop. Below is some relevant information: 1. Sensor: A sensor (English name: transducer/sensor) is a detection device that can sense the measured information and convert it into electrical signals or other required forms of output according to certain rules, to meet the requirements of information transmission, processing, storage, display, recording, and control. 2. Features: The characteristics of sensors include miniaturization, digitization, intelligence, multifunctionality, systematization, and networking. It is the primary link in achieving automatic detection and automatic control. The existence and development of sensors have given objects senses such as touch, taste, and smell, making them gradually come to life. They are usually classified into ten major categories based on their basic sensing functions: thermal elements, photosensitive elements, gas-sensitive elements, force-sensitive elements, magneto-sensitive elements, humidity-sensitive elements, sound-sensitive elements, radiation-sensitive elements, color-sensitive elements, and taste-sensitive elements.
I've been repairing cars for over a decade and have encountered many cases of B12 engines reporting no crankshaft position signal. Usually, it's a faulty crankshaft position sensor. This component is installed near the flywheel at the bottom of the engine and is responsible for detecting the crankshaft's rotation angle and speed, informing the ECU of the ignition timing. The sensor may be dirty, aged, or have incorrect magnetic gap, leading to signal loss; oil sludge coverage or water ingress can also interfere with sensing. Loose, corroded, or broken wiring connectors are common issues, especially since the front wiring harness often suffers from vibration wear. ECU receiver abnormalities are rare but should also be checked. It's recommended to first clean the sensor and connector, then use a multimeter to check if the resistance value is within the normal range of 0.5-1kΩ. If not, replace the sensor. Delayed repairs can result in the engine failing to start or experiencing unstable acceleration, posing significant safety risks. After repair, remember to maintain the engine regularly to avoid oil buildup.
My B12 car displayed this error last year, which really threw me off. A 'no signal from crankshaft position sensor' usually means the sensor is faulty or there's a wiring issue. In my case, engine oil had seeped into the sensor, causing it to malfunction. Sometimes, corroded connectors can also disrupt the connection. Although rare, an ECU fault might trigger a false alarm. For DIY checks, first turn off the engine, locate and remove the sensor for inspection, clean off any debris, and try again. Simple tools like a multimeter can measure resistance—if it's below 500Ω, the sensor is likely faulty. Replacing the sensor fixed the issue. The repair is inexpensive but time-consuming; ignoring it can lead to ignition problems and difficulty starting.
