Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car has a special 'listening' device that helps it run smoothly. If you get this code, it means that one of these devices isn't working right. It's like trying to listen to your favorite song with a broken speaker.
The knock sensor detects vibrations caused by engine knocking and sends a signal to the engine control module (ECM) to adjust the ignition timing. This code indicates a problem with the circuit for the fifth knock sensor.
The P135D code is set when the ECM detects a malfunction in the electrical circuit of the knock/combustion vibration sensor 5. This sensor plays a crucial role in monitoring engine vibrations to prevent knocking, which can damage the engine over time.
• Check Engine Light is on
• Poor engine performance
• Increased fuel consumption
• Faulty knock sensor
• Wiring issues such as open or short circuits
• Faulty ECM
ECM: Engine Control Module
Knock Sensor: A device that detects engine knocking
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the knock sensor for proper operation.
• Replace the faulty knock sensor.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Socket set
$150 - $400
Moderate
• BMW 3 Series
• BMW 5 Series
• BMW X5
• Regular maintenance checks
• Ensure proper engine tuning
• Use quality fuel
Sensor Issue
• Address the issue promptly to avoid engine damage.
• Consult a professional mechanic if unsure.
Check your vehicle's warranty for coverage on engine sensors.
This code has been more common in vehicles with higher mileage and those that have not had regular maintenance.
Moderate – Should be addressed soon to prevent potential engine damage.
Ignoring this code may lead to engine damage and increased emissions, which could be illegal in some regions.
• Engine running
• Vehicle at operating temperature
Typically located on the engine block or cylinder head.
Q: Can I drive with a P135D code?
A: It's not recommended as it may lead to engine damage over time.
Q: How do I reset the P135D code?
A: After repairs, use an OBD-II scanner to clear the code.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.
Fitment Required · Vehicle-fitment part
Commonly relevant for misfire, ignition-efficiency, and some drivability-related repairs.
Misfire and ignition-related faults commonly involve spark plugs as part of the repair path.
Check the correct plug type, gap, and engine application for your vehicle.
View options on Amazon
Fitment Required · Vehicle-fitment part
Relevant when the fault points toward ignition-coil performance or cylinder-specific ignition issues.
Some ignition faults involve coil performance or cylinder-specific coil problems.
Match the coil to your engine and confirm the failed component before ordering.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.