BMW Exhaust Camshaft Problem
“It just doesn’t feel right.”
That was the concern raised by Mr J, who operates a local used-car dealership.
A customer had brought back a BMW 118i that had recently been sold, after noticing a BMW 118i rough idle problem and repeated BMW engine warning light messages… Which is far from ideal.
However, the checks carried out by the used-car dealership couldn’t identify a clear explanation.
With no obvious cause found, Mr J decided to bring the BMW to our expert technicians at Garden City Garage, Seven Sisters, for further investigation.
Although the cause wasn’t immediately clear, the symptoms suggested a fault that needed a structured diagnostic approach. That process led us to uncover a BMW exhaust camshaft problem affecting overall engine operation.
Here’s how the issue was identified, confirmed, and resolved to restore smooth, consistent performance.
Early Checks to Understand the BMW 118i Rough Idle Concern
When the BMW 118i arrived at Garden City Garage, Seven Sisters, our technicians began by listening to Mr J’s account and then confirmed the symptoms through a structured review.
Mr J explained that the BMW had been running unevenly at idle, displaying a BMW engine warning light, and intermittently showing a drivetrain malfunction message. He then explained that he’d checked the vehicle but couldn’t identify a clear cause. So our experts knew to focus on reviewing the vehicle’s systems.
Using this background information, our initial assessment involved:
- A visual inspection under the bonnet to check for disturbed components or signs of recent work.
- A full system scan using the official BMW manufacturer data to review stored and active fault codes.
- A controlled engine start to observe idle quality and general engine behaviour.
The visual inspection didn’t reveal a clear cause, so our team progressed to analysing the fault code information.
The scan highlighted two fault codes directly linked to the reported concerns:
- 130304 – VANOS exhaust cam jammed
- 160021 – Crankshaft sensor loss of synchronisation
(VANOS is BMW’s term for its variable valve timing system, which adjusts camshaft positioning to support efficient engine operation.)
Together, these findings confirmed three key points:
- The crankshaft and camshaft timing signals were no longer aligned.
- A fault was affecting exhaust camshaft control and VANOS operation.
- The BMW 118i rough idle and BMW engine warning light were part of the same underlying issue.
While the fault codes matched the symptoms reported by Mr J, further testing was required to uncover the cause of this BMW exhaust camshaft problem.
Identifying the Cause Behind the BMW 118i Camshaft Issue
With earlier checks confirming VANOS and synchronisation-related problems, the next step of our investigation was to examine the BMW 118i engine timing system in greater detail. Faults in this area can often arise from multiple sources, so a structured diagnostic approach was required.
Using BMW technical data and guided testing procedures, our BMW experts followed a clear process:
- Check engine timing electronically using an oscilloscope to compare camshaft and crankshaft signals.
- Remove the rocker cover and associated components to allow direct inspection of the timing system.
- Review the VANOS components to determine whether the fault involved the control valves, pulley mechanism, or the camshaft.
The oscilloscope readings marked a key stage in the investigation. The signal patterns confirmed the BMW had incorrect exhaust camshaft timing, helping rule out a sensor-related issue and prompting mechanical inspection.
To confirm this, the rocker cover and high-pressure fuel injectors were removed, providing access to the camshaft and timing assembly. This allowed accurate physical timing checks to be completed.
Both the electronic and mechanical analyses pointed to the same conclusion:
The exhaust camshaft was not reaching the correct position in relation to the crankshaft.
Additional checks then focused on the systems responsible for adjusting and monitoring exhaust camshaft timing.
Our team identified two related faults:
- A fault within the system responsible for adjusting exhaust camshaft timing, preventing the camshaft from being positioned correctly.
- An issue with how the exhaust camshaft’s position reference signal was being interpreted.
Because of this, the engine control system couldn’t consistently match the requested camshaft position with its actual position. This caused incorrect valve timing, most noticeable at idle, and triggered the BMW engine warning light, uneven running, and the drivetrain malfunction message.
With the cause of the BMW exhaust camshaft problem confirmed, the next step was to carry out the repair needed to restore correct engine timing and reliable operation.
Resolving the BMW Exhaust Camshaft Problem on the BMW 118i
Once the cause of the BMW exhaust camshaft problem had been confirmed, our BMW technicians contacted Mr J to clearly explain the findings and outline the work required to restore correct exhaust camshaft timing.
This ensured he understood what was causing the issue and what repairs would be needed to resolve it.
At Garden City Garage, Seven Sisters, no work goes ahead until everything has been discussed and agreed. This keeps you informed and in control at every stage.
After reviewing the findings with our team, Mr J approved the recommended repairs and gave us the go-ahead to proceed.
With authorisation in place, our experts sourced high-quality BMW replacement components and began repairing the issue, following BMW procedures carefully throughout.
The repair was completed in the following stages:
1. Removing the affected timing components
To gain access to the faulty components, the necessary upper engine parts were removed in line with BMW repair guidance. This enabled the exhaust camshaft timing components to be removed safely and correctly, preparing the vehicle’s engine for repair.
2. Installing the replacement exhaust camshaft and timing components
The replacement exhaust camshaft and associated timing parts were fitted in accordance with BMW manufacturer procedures. This ensured correct positioning and reliable operation once the engine was reassembled.
3. Renewing supporting timing-control components
Related timing-control components, including parts of the VANOS system, were renewed during the repair to support effective camshaft operation after reassembly.
4. Setting and confirming engine timing using BMW timing tools
With the BMW’s new components installed, engine timing was set and verified to confirm the camshaft and crankshaft were correctly synchronised in line with BMW specifications.
5. BMW 118i Engine Component Reassembly
After timing checks were completed, our technicians carried out full engine reassembly in line with BMW procedures, ensuring every component was refitted accurately and securely.
With reassembly complete, the BMW 118i was ready to move into the final confirmation stage.
Verifying the BMW 118i Was Running Correctly Again
Once the BMW 1 Series engine repair was complete, our BMW experts conducted a series of checks to confirm that the camshaft timing issue had been resolved and that the engine was operating correctly.
As part of this final confirmation stage, we:
- Verified camshaft and crankshaft timing once the engine was fully reassembled.
- Completed system checks to confirm no related faults remained.
- Observed engine behaviour at idle and during a controlled road test.
These checks confirmed that the correct exhaust camshaft timing had been restored, that idle stability had returned, and that the drivetrain malfunction message was no longer present.
After completing the checks, we contacted Mr J to confirm the outcome. He was pleased with the work carried out and confident the BMW was operating as it should.
He left Garden City Garage, Seven Sisters, with the BMW running smoothly, with no further BMW exhaust camshaft problem and no BMW engine warning lights present.
BMW Exhaust Camshaft Problem? Book Your BMW Check-Up at Garden City Garage
If your BMW 1 Series has a rough idle fault or is showing an engine warning light, it’s important to have it checked before the issue develops further.
BMW engine timing issues can occur in many different ways. Identifying the root cause of the problem early can help reduce the risk of further damage and avoid more costly BMW 1 Series engine repair down the line.
This is why accurate testing from a BMW expert is essential.
At Garden City Garage, Seven Sisters, our team uses BMW technical data, manufacturer-grade technology, and hands-on experience to investigate BMW exhaust camshaft problems, BMW VANOS failures, and wider BMW engine timing issues.
Here’s why drivers across Seven Sisters, Neath, South Wales, and the nearby areas choose Garden City Garage for BMW 1 Series engine repair:
- BMW experts working on your vehicle.
- Repairs backed by a 12-month parts and labour guarantee.
- Honesty and transparency, keeping you in the know.
Join the {{review-count}} other drivers who’ve rated us {{average-rating}} stars on Google for excellent value and accurate repairs.
If your BMW shows signs of a timing issue or an engine warning light, contact our BMW experts at Garden City Garage, Seven Sisters on 01639 701604 today.
