Problems and features with Denso control unit 1750002924 / Lexus LS 400.
Analog codes:
| Manufacturer/System: | Analog Number: |
|---|---|
| Denso | 1750002920 |
| Denso | 1750002921 |
| Denso | 1750002922 |
| Denso | 1750002923 |
| Lexus / Toyota OEM | ECU with similar hardware platform |
| OEM version | Different software index |
| Service exchange | Reference number by housing |
The Denso 1750002924 control module is a key element in the electronic architecture of the Lexus LS 400, a model renowned for its reliability, comfort and engineering precision. Despite the high quality of workmanship and components used, as the years and mileage accumulate, this type of electronic unit can begin to exhibit various performance deviations. These problems often develop gradually, without sudden and definite failure, making diagnosis and interpretation of symptoms particularly challenging.
One of the characteristic features of this module is that most of the complaints do not occur consistently. Lexus LS 400 owners often report intermittent behavior - the vehicle runs normally for days or weeks, then suddenly engine disturbances occur. This may manifest itself in an unstable idle, a short interruption on acceleration, or difficulty starting for no apparent reason. Such behaviour gives the impression of an external problem that is difficult to reproduce in service conditions.
Defects/Symptoms
Symptom: | Manifestation at the car: | Characteristics: |
|---|---|---|
| Tough start | Prolonged rotation before ignition | Intermittently |
| Unstable idle | Speed fluctuations | More pronounced in cold engine |
| Cut-off on acceleration | Short-term loss of traction | Under load |
| Slow pedal response | Lack of direct reaction | No consistent pattern |
| Increased fuel consumption | Without mechanical causes | Gradual deterioration |
| Sporadic extinction | Most often at low speed | No permanent error record |
| Uneven engine operation | Altered sound and vibration | Intermittently |
| Check Engine Light | Temporarily, without clear reason | Disappears on its own |
Another common aspect is altered engine response to load. In normal driving, the car may behave perfectly adequately, but when the throttle is applied sharply or when driving under load, there may be a delay in response or uneven power development. These symptoms are rarely accompanied by a clear indication on the dashboard and in many cases do not lead to activation of the emergency mode, which further complicates the diagnostic process.
Deviations related to mixing management may also be observed at more advanced module age. This manifests itself as increased fuel consumption or a slightly altered engine sound, with no mechanical defects or fuel system problems. In such cases, standard sensor and actuator checks often show no abnormalities, which draws attention to more general behaviour of the control electronics.
Errors / DTC
| DTC code: | Description: | General character: |
|---|---|---|
| P0100-P0102 | Debit meter - incorrect signal | Interrupt/unstable input |
| P0110-P0115 | Air temperature | Unrealistic values |
| P0120-P0123 | Throttle position | Mismatch between signals |
| P0170-P0175 | Fuel mixture regulation | Outside permissible limits |
| P0300 | Accidental gaps in ignition | Without a specific cylinder |
| P0335-P0339 | Crankshaft sensor | Loss of synchronization |
| P0340-P0345 | Camshaft sensor | Intermittent signal |
| P0600-P0606 | Internal communication | Illogical behaviour |
| P1600-P1604 | ECU power supply | Sporadic restarts |
It is also a characteristic of Denso 1750002924 that the errors that can be recorded in diagnostics do not always reflect the real cause of the problem. Sometimes codes are recorded relating to peripheral components that are actually functioning within normal limits. This can lead to unnecessary replacement of faulty parts and prolong the time to find the true source of symptoms. In other cases, no permanent faults are recorded despite distinct operating complaints.
Over time, problems can also occur with the communication between the different systems of the vehicle. The Lexus LS 400 uses a relatively sophisticated electronic architecture for its time, where reliable data exchange between modules is essential. When this process becomes unstable, the consequences can be unexpected, ranging from sporadic illumination of warning lights to temporary restriction of certain functions without clear explanation to the driver.
It is important to note that in many cases, symptoms are exacerbated under certain conditions - for example, at a high temperature in the engine compartment, after prolonged driving or after a standstill. This gives the impression of a problem dependent on external factors, which often misleads even experienced technicians. The vehicle may be fully upright on a cold start and short run, but exhibit instability after reaching operating temperature.
Because of all these features, the approach to diagnosis and servicing of a Denso 1750002924 module must be systematic and careful. The focus should not fall solely on individual components or faults, but on the overall behaviour of the system. Analysis of symptoms over time, the conditions of occurrence and their frequency often provides much more valuable information than a single diagnostic reading.
In our practice it has been found that , these modules often flood and have corrosion and internal defects with other systems.
