Saab 9-3 II, Opel Vectra C & Signum - Issues with the Engine Control Unit (B207E/L/R & Z20NET)

Saab 9-3 II, Opel Vectra C & Signum - Issues with the Engine Control Unit (B207E/L/R & Z20NET)

The flagship of our company is the repair of Trionic 8, which we have been successfully performing as the world's first company since last year. But when is the engine control unit actually defective? Every diagnosis inevitably begins with reading the error codes. We often receive inquiries about whether we can repair the control unit because it does "XYZ." However, it's a bit like visiting a doctor. If you don't talk to the doctor, he won't know what's wrong with you. The same goes for engine control units. Contrary to popular belief, the reading doesn't have to be done with a Tech2. Any tester from the hardware store does the job! If in doubt, it's, of course, best to consult a workshop.

In general, the following "standard errors" exist:

  • P0118
  • P0201
  • P0202
  • P0203
  • P0204
  • P0245
  • P0246
  • P0601
  • P0606
  • P0638
  • P0686
  • P0687
  • P0691
  • P0692
  • P0693
  • P1682
  • P2135

P0601 & P0606

This error manifests itself in two ways. Either the vehicle doesn't start at all, or it only starts when it's cold. The causes range from faulty memory contents to a complete failure of the main memory. For those who think they can just casually solder the memory chip (also known as EEPROM), they should take a look at the work of "professional" competitors.

Hard to imagine, but indeed the work of a "professional" repair shop.

Even the act of opening these control units is an extremely delicate matter, as there is no traditional printed circuit board (PCB) in the conventional sense, but rather a flex PCB (flexible printed circuit board). Improper opening not only leads to the immediate rupture of the casing (which is inevitably unavoidable with repeated openings in the long run) but also frequently results in total damage to the flexible PCB or, as seen above, individual components.

A cleanly removed memory chip.
The new memory chip finds its home cleanly and precisely soldered. We exclusively and demonstrably use new components from the manufacturer.

In comparison, the quality of our work stands out. Not only do we open the casing without causing damage, but our work is precise and clean. You will soon see just how precise we can be in another article about V6 control units for the 2.8T variant of the Saab 9-3 II and Opel Signum / Vectra C.

P0201, P0202, P0203, P0204, P0245, P0246

These errors are particularly easy to identify because they usually occur together. Despite the straightforward diagnosis, there has been a faulty video circulating for years that promises a solution. In the video, the so-called TPIC (main injector driver) is replaced. After that, the vehicle runs - and that's true. However, the creator doesn't mention anything about the durability of the repair, as there is a vested business interest.

The trick lies precisely there. If you replace the main injector driver, the vehicle is temporarily quiet, but in 95% of cases, the error reoccurs in less than 6 months. Even if some eBay offers come with a warranty, it's of no use if the root cause is not addressed.

Especially customers in the USA suffer total losses of their control units due to repairs carried out with the same inferior quality as mentioned above or sometimes even fire damage caused by low-quality components.

P0686, P0687, P0691, P0692, P0693

These error codes often manifest themselves through non-starting fans. While most errors require a repair of the control unit, it's still not uncommon for the problem to be more trivial. We recommend our customers to check the main relay and the fan control fuse in such cases. Occasionally, it may even be necessary to replace the fans entirely, although, in our previous experience, this has been limited to isolated cases.

For this error code as well, there are unscrupulous individuals who claim to fix the problem with a "software patch." We strongly advise against such offers, even if they are offered for free.

There have also been cases of fire damage caused by exactly this "solution." Accordingly, we consider such attempts extremely dangerous, even life-threatening!


An error of superlatives - with a total of 32 potential sources of error on the circuit board, this error is certainly not one of our favorites. As a basic approach, we recommend taking action only in case of a problem. Since this error is not very informative on its own, we prefer to offer the customer a free loan device and then ask for feedback.

There are also supposed software solutions for this unpleasant error. Unlike P0686 & P0687, these are not life-threatening, but they are also not promising in terms of success. Disabling this error code in the long run leads to an electrical overload of the throttle valve. Depending on the model year, it can be difficult to obtain such a replacement part. Not to mention the additional costs involved.

P0638 & P2135

Despite their known cause, these error codes are currently considered unreparable. We are still working on a solution but cannot provide a timeline due to the high technical complexity. Nevertheless, these errors do not necessarily mean that the control unit is no longer functional. It could also be related to the throttle valve.

Another potential source of the error, apart from the control unit and the throttle valve, is the connector of the engine wiring harness under the battery box. The pins on the connector (H42-2) there tend to lose their connection strength. Saab was aware of the problem back then and addressed it with appropriate bulletins.

Avoiding pitfalls

As you can see, there are many providers without the necessary quality. But how do you find a reputable repair service? It's clear that there is no one-size-fits-all rule. However, there are indicators you can look for. Primarily, it's about protecting your consumer rights and how you are treated.

We do not require any upfront payment from our customers (except for third countries, where we conduct transactions step by step), and we offer free loan devices in immediate exchange until you receive your control unit back. Only when the customer confirms functionality do we request payment, or at the latest, after 3 days. If something comes up in the meantime, we do not issue an invoice until the problem is resolved.

Warranty and guarantees also play a role. While some companies advertise with "lifetime" warranties, remain realistic. If something sounds too good to be true, it may not be a serious offer. This may not apply to all repairs, but at least for the Trionic 8. Since we focus on "treating" the issues like doctors, we do not offer complete refurbishment. We work minimally invasive, ensuring a reproducible result. As mentioned above, indiscriminately changing components can lead to issues being masked.

However, our warranty not only covers our actual work but also includes free rework for other repairable fault codes within the warranty period.

Another factor to consider is the testing procedures. Of course, very few companies reveal all their "secrets." However, with us, you can rest assured that no control unit leaves our premises without being tested in one of our test vehicles.

This testing process is time-consuming, but it provides maximum security for the customer.