Diagnostic Result
Diagnostic Trouble Code (DTC / OBDII): No DTC provided, further diagnostic scanning is required.
Vehicle: Ford Focus Mk3 (2015) EcoBoost/TDCi with Direct TPMS
Detailed: Focus Mk3(2015)Eco Check Tyre Pressure Warning comes on.
I keep getting the warning after about 10 mins. My understand is the batteries only last 10 years, so about two months ago I all 4 sensors replaced.
All was ok for a few weeks. Now the warning comes on immediately, my understanding is that the tyres don't talk to the ECU for about the first 10 minutes.
I went to another tyre dealer & had all 4 sensors read, they are all ok.
So my thoughts were I should reset the ECU. So today I disconnected the battery, shorted out the + & - cables & left it in that state for 30mins. Followed all the info on reconnecting the battery & letting the engine run so the ECU relearns.
Still get 'Check Tyre Pressure' warning immediately.
Anyone had similar problem or can help.
It need to be done as its an MOT failure.
Most Likely Causes (High Priority)
- TPMS Sensor Re-learn Procedure Failure (9 Pts)
After replacing the tire pressure monitoring system (TPMS) sensors, the vehicle's Body Control Module (BCM) or dedicated TPMS control unit needs to 'learn' the unique identification (ID) codes of the new sensors. If this re-learn procedure was not successfully completed or if the learned IDs were subsequently lost (perhaps due to a module glitch), the system will not recognize the sensors, leading to an immediate 'Check Tyre Pressure' warning. The initial 'ok for a few weeks' suggests a temporary learning that might have reverted.
- Faulty TPMS Control Module or Receiver Antenna (8 Pts)
The component responsible for receiving wireless signals from the tire pressure sensors (either a standalone TPMS module or integrated within the Body Control Module) may be malfunctioning. If this module, or its dedicated antenna, is faulty or has an internal defect, it will fail to receive valid data from the transmitting sensors, causing the system to trigger an immediate warning regardless of the sensors' operational status. This would explain why external tools can read the sensors but the car cannot.
- Wiring Harness or Connector Issue (7 Pts)
Damage, corrosion, or a loose connection in the electrical wiring harness or connectors leading to the TPMS control module or its antenna(s) can interrupt communication. This communication breakdown prevents the vehicle's system from receiving or processing the tire pressure data, resulting in a persistent warning message. Physical inspection of these components is crucial.
Recommended Verification Steps
Perform a Comprehensive Diagnostic Scan: Connect an advanced diagnostic scan tool (e.g., Ford IDS or FORScan) to the vehicle's OBD-II port. Read all Diagnostic Trouble Codes (DTCs) from the Body Control Module (BCM) and any specific TPMS module. This will provide specific fault codes that pinpoint the exact nature of the problem, which is crucial since no DTC was provided initially.
Execute TPMS Re-learn Procedure: Using a suitable diagnostic tool, initiate and complete the official Ford TPMS re-learn procedure for your 2015 Focus Mk3. This process typically involves placing the vehicle in 'learn mode' and then activating each tire pressure sensor sequentially. Monitor live data during this process to confirm that each sensor ID is being learned by the vehicle.
Inspect TPMS Module/Antenna & Wiring: Physically locate and inspect the TPMS control module (often integrated into the BCM, typically behind the glove box or passenger footwell) and its associated wiring harnesses and connectors. Look for any signs of physical damage, corrosion, or loose connections. If external TPMS antennas are used (less common for Mk3 Focus but good to check), inspect them similarly.
Verify Sensor Compatibility and Signal: Although another dealer confirmed the sensors are 'ok,' use a dedicated TPMS activation tool to re-verify each sensor's ID, battery status, and signal strength while the tires are mounted. Also, double-check that the replacement sensors are the exact correct part number and operating frequency (e.g., 433 MHz for Europe) specified for your 2015 Ford Focus Mk3.
Expert Summary:
Your Ford Focus Mk3 (2015) is displaying an immediate 'Check Tyre Pressure' warning despite recent sensor replacement and confirmation that the sensors are transmitting. This indicates a likely issue with the vehicle's ability to receive, process, or correctly 'learn' the new sensor data. The primary suspects are an unsuccessful or lost TPMS re-learn procedure, a faulty TPMS control module or its receiver antenna, or a problem within the associated wiring. A professional diagnostic scan for specific TPMS fault codes and a proper re-learn procedure are the critical next steps to accurately diagnose and rectify this MOT-critical fault.
