BMW Exhaust Camshaft Problem
“Something doesn’t add up with how it’s running.”
That was what Mrs A said to our experts when she brought a BMW 118i to us.
Mrs A runs a local used-car dealership, and the BMW 118i had been returned by a customer not long after purchase. The vehicle had a rough idle and a persistent engine warning light.
Initial checks performed at the used-car dealership hadn’t explained why the issue was occurring.
To get to the bottom of the issue, the vehicle was brought to our team at RS Autotechnik, Dursley, for a more detailed assessment.
Although there was no immediate answer, the symptoms pointed towards a deeper issue within the engine system. A structured investigation followed, confirming a BMW exhaust camshaft problem affecting engine timing and idle quality.
Here’s how we traced the fault, identified the cause, and restored normal engine operation.
How We Began Diagnosing the BMW 118i Rough Idle
When the BMW 118i was brought into RS Autotechnik, Dursley, our technicians began by listening to Mrs A’s experience with the issue. Once we understood what she was experiencing, we moved on to confirming the symptoms through a structured assessment process.
She reported that the BMW had been showing an engine warning light, running unevenly at idle, and displaying a drivetrain malfunction message.
However, previous checks performed at her used-car dealership hadn’t explained why this was happening. To help get to the bottom of the issue, our role was to uncover what the engine control systems were signalling.
Using this background information, our initial checks included:
- Carrying out a visual inspection under the bonnet to identify disturbed parts or signs of prior work.
- Running a full system scan with BMW manufacturer data to assess stored and active fault codes.
- Performing a controlled start-up to observe engine behaviour while idling.
As no obvious cause was found during the visual inspection, our focus moved to analysing the fault code data.
The scan revealed two fault codes that directly matched the symptoms:
- 130304 – VANOS exhaust camshaft jammed
- 160021 – Crankshaft sensor loss of synchronisation
(VANOS is BMW’s variable valve timing system, which adjusts camshaft positioning to support efficient engine performance.)
These fault codes provided three clear insights:
- The camshaft and crankshaft were no longer operating in sync.
- The engine management system had identified a problem with exhaust camshaft control.
- The BMW engine warning light and rough idle were part of the same engine issue.
While this confirmed the presence of a fault, fault codes alone don’t reveal why the vehicle is rough idling in the first place. Further testing was needed to determine the cause of this BMW exhaust camshaft problem.
What Was Causing This BMW Exhaust Camshaft Problem?
With BMW’s VANOS and synchronisation faults confirmed during the initial checks, our team’s focus shifted to a closer review of the BMW 118i engine timing system. Given the number of potential causes, a structured, evidence-based process was required.
Using BMW technical data and guided testing procedures, our BMW experts followed a clear approach:
- Checking camshaft and crankshaft timing electronically by analysing their signal relationship.
- Removing the rocker cover and associated components to carry out a direct inspection of the timing assembly.
- Reviewing the VANOS system to establish whether the issue lay with the valves, pulley, or camshaft itself.
The electronic timing checks provided the first key indication. The signal patterns indicated incorrect exhaust camshaft timing and suggested a fault not purely sensor-related, leading us to proceed with a mechanical inspection.
To confirm this, the rocker cover and high-pressure fuel injectors were removed, giving full access to the camshaft and timing assembly and allowing precise physical timing checks.
Both electronic and mechanical testing revealed the same outcome…
The exhaust camshaft wasn’t reaching the correct position in relation to the crankshaft.
Further investigation focused on the systems responsible for controlling and monitoring exhaust camshaft timing.
Two related faults were identified:
- A fault within the exhaust camshaft timing adjustment system was preventing accurate positioning.
- The exhaust camshaft position reference wasn’t being read correctly.
As a result, the vehicle’s engine control system couldn’t consistently align the requested camshaft position with the actual position. This resulted in incorrect valve timing at idle, leading to rough running, a BMW engine warning light, and drivetrain malfunction messages.
With the root cause of the BMW 118i rough idle confirmed, the next step was to carry out repairs to restore correct camshaft timing and engine operation.
How Our Team Repaired the BMW Exhaust Camshaft Problem
With the BMW 118i rough idle fault confirmed, our technicians discussed the findings with Mrs A, explaining what was preventing correct camshaft timing and how we planned to resolve the issue.
This ensured she understood the exact cause of the problem and what work would be required to put it right.
At RS Autotechnik, Dursley, work only proceeds once everything has been explained and approved. This keeps you informed and involved throughout the entire repair process.
Mrs A was pleased we’d found the cause of the issue and gave our team the green light to proceed with the repair.
Following approval, our technicians sourced high-quality BMW replacement components and carried out the repair methodically, following BMW procedures throughout.
The repair involved the following stages:
1. Removing the affected timing components
The necessary upper engine components were removed in line with BMW repair guidelines to allow our team to access the exhaust camshaft timing components.
2. Installing the replacement exhaust camshaft and timing components
The replacement exhaust camshaft and related timing components were installed according to BMW manufacturer procedures to ensure correct positioning.
3. Renewing related timing-control components
Related timing-control components, including elements of the VANOS system, were renewed to support correct camshaft operation.
4. Setting and verifying engine timing using BMW timing tools
Engine timing was set and verified to confirm proper synchronisation between the camshaft and crankshaft.
5. BMW 118i Engine Reassembly
With the timing confirmed, our team of BMW experts fully reassembled the vehicle’s engine in accordance with BMW procedures.
With the engine repair now complete, the vehicle was ready for the final stage of our repair process… Confirming it had been successful.
How We Confirmed The BMW Exhaust Camshaft Problem Repair
Once repairs were complete, our technicians conducted a series of checks to confirm that the camshaft timing issue had been fully addressed and that engine operation had been restored.
This final confirmation stage included:
- Verifying camshaft and crankshaft timing after reassembly.
- Running system checks to ensure no related faults remained.
- Observing engine performance at idle and during a controlled road test.
These checks confirmed that the BMW exhaust camshaft timing was correct, the rough idle problem had been resolved, and the drivetrain malfunction message no longer appeared.
With this confirmation in place, our team called Mrs A to inform her of the outcome. She was satisfied with the repair and confident that the BMW was back to normal operation.
The BMW left RS Autotechnik, Dursley, running smoothly, with BMW engine warning lights cleared and BMW engine timing issues resolved.
BMW Exhaust Camshaft Problems? Book a BMW Check-Up at RS Autotechnik
When your BMW starts showing uneven running or an engine warning light, it’s often an early sign of an underlying engine timing issue.
BMW engine timing issues can develop in several ways, and early investigation by a BMW expert can help reduce the risk of more complex BMW 1 Series engine repair work later. A thorough BMW check-up helps provide clear answers and confidence.
At RS Autotechnik, Dursley, our technicians are BMW experts with access to official BMW technical data and manufacturer-grade technology to investigate BMW exhaust camshaft problems, BMW VANOS failures, and related timing concerns.
Here’s why drivers across Bristol, Tetbury, and Gloucester choose RS Autotechnik for engine repairs:
- A courtesy car is available to minimise disruption.
- BMW engine repair experience.
- A 12-month parts-and-labour guarantee covers all repairs.
Join the {{review-count}} other drivers who’ve rated us {{average-rating}} stars on Google for accurate repairs and value.
If your BMW is showing signs of an engine timing issue, contact RS Autotechnik, Dursley, on 01453 796345 to book your BMW check-up.
