A 2017 Range Rover (L405) came in with two warnings on the cluster that no owner wants to see together: “Air suspension not in customer mode” and a red hydraulic warning.
On paper it looked like two separate failures — one in the air suspension, one in the hydraulics — with five fault codes to go with them. In the end it was one failed part. Here's how we got there, and why the fix wasn't where the codes seemed to point.
What the cluster showed
The first message means the suspension system isn't in its normal customer operating mode — something you'd normally only see during calibration or other service work. The red one is the hydraulic side: on this L405 that's the Dynamic Response system, the hydraulic active anti-roll setup that keeps the body flat in corners.
What the scan showed
The fault memory held five codes across three areas — module configuration, air suspension and hydraulics:
| Code | System | What it points to | Failure type |
|---|---|---|---|
| P1905 | Module | Control module configured for end-of-line (factory test) mode | — |
| C1A13-64 | Air suspension | Gallery pressure not dropping as expected when the system vents | 64 · signal plausibility |
| C1119-09 | Hydraulics | Hydraulic pressure | 09 · component failure |
| C104A-94 | Hydraulics | Pressure-regulating valve | 94 · unexpected operation |
| C104C-94 | Hydraulics | Pressure-regulating valve | 94 · unexpected operation |
Descriptions are summarized; exact wording varies by module and software level. The suffix is the failure type: -09 component failure · -64 signal plausibility failure · -94 unexpected operation.
Why this combination is a trap
Read code by code, this scan writes its own shopping list. C1119 says hydraulic pressure — so a pump or a pressure sensor. The C104A / C104C pair says pressure-regulating valves — so a valve block. C1A13 points at air-suspension pressure — so a compressor, an air valve block or a leak. Every one of those is an expensive part, and on this car none of them was the problem.
The clue was in the line that didn't fit the shopping list. P1905 means a control module is reporting a factory test configuration instead of normal operation — and the cluster was saying the same thing in plain English: the suspension wasn't in customer mode. When a module that can't settle into its normal mode sits on top of pressure and valve faults in the system it controls, the module itself belongs on the suspect list.
Replace the pump. Then the valve block. Then the air-suspension parts — clearing codes after each one. It's the most expensive way to diagnose a Range Rover, and on this car it would have ended with the same warnings on the cluster.
How we fixed it
- 01
Scan
Five codes — P1905, C1A13-64, C1119-09, C104A-94, C104C-94 — with “Air suspension not in customer mode” and the red hydraulic warning on the cluster.
- 02
Adaptations
We ran the suspension and hydraulic adaptations and calibration routines with dealer-level software. On a healthy system, that's often the whole fix. Here it wasn't.
- 03
Root cause
Based on our experience with these systems, we looked past the hydraulic parts to the electronics that run them — and found it: the second hydraulic control module had failed.
- 04
New module
We installed a new module and ran the software updates.
- ✓
Result
Everything works: the suspension is back in customer mode, the hydraulic warning is gone and the system operates as it should.
Which module — and why adaptations alone couldn't fix it
On the L405, the hydraulic Dynamic Response system has its own control module — the second chassis control module, listed in Land Rover diagnostics as CHCMB (Chassis Control Module B). That's the unit that had failed.
Adaptations and calibrations are as much a test as a fix. When a routine won't stick, or a system won't stay in customer mode afterwards, something underneath is wrong — and you can't calibrate your way out of failed hardware. A new module doesn't simply plug in either: it has to be set up for the car and brought to the right software level, which is why the updates were part of the job, not an afterthought.
What this case teaches
- Codes describe what a module sees, not which part failed. Five codes here, one root cause.
- When two systems complain at once, look at what they share — a control module, power, the network — before buying parts for either.
- “Not in customer mode” isn't always just a setting. Often it's a mode left on after service or calibration; sometimes it's the first sign that a module has failed.
- Diagnosis is the cheap part. One new module and software updates instead of a pump, a valve block and air-suspension parts.
Seeing the same warnings on your Range Rover?
Don't keep clearing the codes, and don't start replacing parts yet. Write down exactly what the cluster says and get every module scanned with dealer-level software — on these cars the combination of codes matters more than any single one.
Treat a red warning as urgent: with the hydraulic anti-roll system faulted, the vehicle can handle differently, especially in corners. Drive gently and have it checked soon.
We handle Range Rover and Land Rover suspension, hydraulic and module faults at our shop at 209 Stafford St in Worcester, MA — call (857) 288-5117 or send us your codes and VIN through the quote form.