Siemens SID804 Engine ECU Fault – Common Cause Of Ford P0652

If you’ve got a 1.4L TDCi Ford Fiesta with an engine warning light on and P0652 stored, there’s a good chance you’ve experienced a common SID804 ECU fault. Thankfully, we’re the experts at remanufacturing these control modules with a lifetime warranty included.

Shop Now – Siemens SID804 Rebuild

While it’s common for the Siemens SID804 to cause P0652 to store in 1.4L TDCi Ford Fiestas, it frequently causes injector circuit faults too. In both cases, engine performance is significantly affected, inevitably leading to a poor idle, misfires, cutting out, limp mode and non-start conditions. 

You’ll find these problematic units wreaking havoc in the fifth-generation (2002-2008) Fiesta as well as the Ford Fusion (2002-2008) – both with 1.4L diesel engines.

Ford P0652 fault explained
The reason the Siemens SID804 is such a frequent cause of issues in these Ford vehicles is due to common internal breakdowns within the ECU. This defect inevitably prevents the control module from carrying out its usual functions effectively, one of which is the supply of a 5V reference to a number of sensors.

While this inevitably leads to a variety of performance issues as mentioned above, one DTC in particular indicates your Ford’s SID804 ECU has malfunctioned:

• P0652 – Sensor Reference Voltage B Circuit Low

You’ll find this code stored in your SID804’s memory when it has malfunctioned, and it indicates a general issue with its sensor reference voltage supply. P0652 isn’t isolated to just one of your Ford’s sensor circuits (like for a MAP or TP sensor), it relates to a shared 5V reference output supplying multiple sensors.

Many vehicle sensors rely on the ECU’s 5V reference supply as a stable baseline to generate their signal output. If this reference voltage is low or unstable, sensor signals become inaccurate or inconsistent, which quickly results in DTCs being logged.

Due to the engine ECU’s internal fault, its ability to activate sensor reference circuits is compromised. Although the SID804 is itself defective, it’s still able to identify a sensor reference circuit fault - which is evidenced by your Ford’s P0652 code.

While it’s always worth verifying wiring integrity, if you’re detecting P0652 alone or alongside various other sensor-related codes, this strongly indicates a Ford SID804 fault. When your diagnostic tool detects a single-sensor DTC without the presence of P0652, you should suspect the sensor in question could be at fault.

For example, it’s particularly common for the P0652 code to be stored alongside P0336 (crankshaft position sensor) and P0191 (fuel rail pressure sensor) too.

If you’re in any doubt whether a defective SID804 engine ECU is the cause of a sensor reference supply DTC like P0652 in your Ford Fiesta or Fusion, send it to us for comprehensive testing. 

How to resolve Siemens SID804 failure 
As the root cause of SID804 failure and your Ford’s P0652 DTC is internal to the ECU, you’ll need to have it remanufactured. 

Many affected owners opt to replace their defective control module with brand new, however this runs the risk of repeat malfunction. This is because the internal defect is often present in replacement SID804 units, inevitably leading to the original issue manifesting itself once again.

The best way to resolve your Ford’s symptoms is to have the SID804 comprehensively remanufactured.

Our solution
Thankfully, we’re the experts at testing and rebuilding these engine ECUs. Simply fill out this test form and we’ll collect your SID804 from you and resolve your Ford Fiesta/Fusion’s P0652 code within 2-3 working days.

Thanks to our custom-built hardware-in-the-loop testing rigs, your SID804 will be examined under realistic operating conditions. This allows us to uncover the root cause of your Ford’s P0652 code accurately and efficiently.

Our expert techs will then get to work rebuilding your defective unit with higher-than-OEM-standard components. Our process preserves all coding information and immobiliser integrity so that you can just refit the ECU as soon as you receive it back.

We cover all rebuilds with an unlimited-mileage lifetime warranty too, meaning you’re covered for good. 

Resolve your Ford Fiesta or Fusion’s P0652 code properly by having your SID804 remanufactured by us – use this test form to get started today. 

Common failure symptoms:

• 5V reference faults
• Injector circuit faults
• No start
• Engine warning light on
• Limp mode
• Rough idle
• Cutting out
• Misfires

Common fault codes:

• P0652 – Sensor Reference Voltage B Circuit Low
• P0336 – Crankshaft Position Sensor Circuit Range/Performance
• P0191 – Fuel Rail Pressure Sensor Circuit Range/Performance

Test and rebuild:
We use specialist custom-built testing rigs to analyse each control module to identify defects with pinpoint accuracy. We even utilise top-grade components in our rebuilds to ensure functionality is restored for good.
 
Programming:
All programming and immobiliser integrity is retained, meaning you can simply refit the rebuilt control module straight away. 
 
Quality:
We strive to provide an excellent service to the industry and this is demonstrated by our proud defect rate of just 0.49%. Thanks to this, we’ve become the chosen provider of automotive control module remanufacturing services for thousands of specialists worldwide. 

Warranty:

Lifetime unlimited mileage*

How do I get my unit rebuilt?

To pay for the rebuild click the Shop Now link above, select your part number and click: Get yours rebuilt.

Print the payment/booking confirmation email.

Package the SID804 ECU inside a sturdy box with plenty of packaging material and make sure you include your confirmation email in the box.

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received we will test, rebuild and return your control module with an unlimited mileage lifetime warranty. If your unit turns out not to be faulty then we will refund your payment less a small testing fee and return shipping.

What if I don’t want to pay up front?

This is not a problem, if you prefer this option then follow these steps:

Fill in and submit this test form.

Print the booking confirmation email.

Package the engine ECU inside a sturdy box with plenty of packaging material and make sure you include your confirmation email in the box.

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received, we will test your unit and call to inform you of the outcome of testing. If your control module is faulty and you choose to go ahead with the rebuild, then we will take payment over the phone using a debit/credit card.

We will then rebuild your ECU and return it to you with an unlimited mileage warranty.

If you require further information regarding this Siemens SID804 ECU fault then please contact us.