BMW Exhaust Camshaft Problem
“Something doesn’t feel right with it.”
That was the concern raised by Mrs N, who manages a local used-car dealership.
A recently sold BMW 118i was returned after the customer experienced uneven idling alongside repeated BMW engine warning light alerts. Checks carried out at the used-car dealership hadn’t identified what was causing the issue.
With no clear explanation for the rough idle problem, Mrs N brought the 118i to our BMW experts at Protech Automotive, Newport, for a more detailed review.
Although the cause wasn’t immediately clear, the symptoms suggested a fault that needed a structured diagnostic approach. What followed was a methodical assessment that led us to uncover a BMW exhaust camshaft problem affecting the engine’s timing.
Below, we explain how the fault was identified, what was causing the BMW 118i rough idle, and how the repair restored smooth, dependable operation.
Our Initial Review to Investigate the BMW 118i Rough Idle
When the BMW 118i arrived at Protech Automotive, Newport, our technicians began by listening to Mrs N’s experience with the vehicle, then confirmed the reported symptoms through a structured assessment.
Mrs N explained that the BMW had been displaying a BMW engine warning light, running unevenly at idle, and intermittently showing a drivetrain malfunction message. Checks previously carried out by the used-car dealership hadn’t identified the cause, so our attention turned to understanding what the vehicle’s systems were reporting.
Using this information, our initial assessment included:
- A visual check under the bonnet to identify any disturbed components or signs of previous work.
- A full system scan using the official BMW manufacturer technical data to review stored and active fault codes.
- A controlled engine start to assess idle stability and overall engine behaviour.
The visual inspection didn’t highlight an obvious explanation, so the fault code data was reviewed in more detail.
Two fault codes were identified that related directly to the reported concerns:
- 130304 – VANOS exhaust cam jammed
- 160021 – Crankshaft sensor loss of synchronisation
(VANOS is BMW’s trademarked name for its variable valve timing system, which adjusts camshaft positioning to support efficient engine operation.)
Together, these findings highlighted three key points:
- A fault affecting exhaust camshaft control and VANOS operation had been detected.
- Crankshaft and camshaft timing were no longer correctly synchronised.
- The BMW 118i rough idle and the BMW engine warning light weren’t isolated symptoms but part of a wider engine-related issue.
While the fault codes aligned with the symptoms, further testing was required to identify the cause of this BMW exhaust camshaft problem.
Identifying the Root Cause of the BMW Exhaust Camshaft Problem
With the initial assessment confirming VANOS-related and synchronisation faults, our expert’s focus shifted to a closer examination of the BMW 118i engine timing system. Faults in this area can develop in different ways, which meant a structured, evidence-led process was essential.
Using BMW technical data and guided testing routines, our technicians followed a clear diagnostic plan:
- Electronically verify engine timing using an oscilloscope to compare camshaft and crankshaft signals.
- Remove the rocker cover and associated components to allow direct inspection of the timing system.
- Inspecting the VANOS components to determine whether the issue involved the control valves, pulley mechanism, or camshaft itself.
The oscilloscope results marked a decisive moment in our team’s investigation. The signal patterns confirmed incorrect exhaust camshaft timing, ruling out a sensor-only issue and leading to mechanical inspection.
To validate this, the rocker cover and high-pressure fuel injectors were removed, providing full access to the camshaft and timing assembly. This allowed precise physical timing checks to be carried out.
Both electronic testing and mechanical measurement pointed to the same conclusion:
The exhaust camshaft was not achieving the correct position in relation to the crankshaft.
Further investigation focused on the systems responsible for adjusting and monitoring exhaust camshaft timing.
Two related faults were identified:
- A malfunction within the exhaust camshaft timing adjustment system prevented correct camshaft positioning.
- An issue affecting how the exhaust camshaft position reference was being interpreted.
As a result, the engine control system couldn’t consistently align the commanded camshaft position with its actual position. This caused incorrect valve timing, particularly at idle, triggering the BMW engine warning light, unstable running, and the drivetrain malfunction message.
With the BMW exhaust camshaft problem confirmed, the next step was to complete the repair needed to restore correct engine timing and normal operation.
Resolving the BMW 118i Exhaust Camshaft Problem
Once the cause of the BMW exhaust camshaft problem had been identified, our BMW technicians contacted Mrs N to clearly explain the findings and outline what would be required to restore correct exhaust camshaft timing.
This ensured she had a clear understanding of what was causing the issue and the work needed to put it right.
At Protech Automotive, Newport, no repairs are carried out until everything has been fully explained and approved, ensuring you stay informed and in control throughout.
Mrs N was pleased our team had found the root cause of the issue and gave us the green light to proceed with the repair. With the authorisation given, our experts sourced suitable BMW replacement components and began the repair, following BMW procedures carefully.
The repair was completed in the following stages:
1. Removing the affected timing components
The upper engine components were removed in accordance with BMW repair guidance, providing safe, direct access to the exhaust camshaft timing components.
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 to ensure accurate positioning and dependable operation.
3. Renewing supporting timing-control components
Related timing-control components, including parts of the VANOS system, were renewed to support consistent camshaft operation after reassembly.
4. Setting and confirming engine timing using BMW timing tools
With the replacement parts installed, engine timing was set and verified to confirm correct synchronisation between the camshaft and crankshaft in line with BMW specifications.
5. Final BMW 118i engine reassembly
With timing confirmed, the engine was reassembled carefully, ensuring all components were refitted correctly and securely.
Following reassembly, the BMW 118i was ready for final confirmation checks.
Confirming Regular Operation After BMW Exhaust Camshaft Repair
Once the repair was complete, our BMW technicians carried out a structured series of checks to ensure the exhaust camshaft timing issue had been fully addressed and the engine was operating as expected.
As part of this final confirmation stage, we:
- Verified camshaft and crankshaft timing following reassembly.
- Completed system checks to ensure no related faults remained.
- Monitored engine behaviour at idle and during a controlled road test.
These checks confirmed that correct exhaust camshaft timing had been restored, the BMW 118i rough idle was resolved, and the drivetrain malfunction message no longer appeared.
With the checks complete, our BMW experts called Mrs N to explain that the repair had been completed and her BMW was ready for collection. She was pleased with the repair work, the clear communication, and the overall experience.
She left our garage with the BMW running smoothly, with no remaining BMW exhaust camshaft problem or BMW engine warning lights present.
BMW Exhaust Camshaft Problem? Book Your BMW Check-Up at Protech Automotive
If your BMW 1 Series is running unevenly at idle or displaying an engine warning light, it’s important to have it checked before the issue progresses.
As BMW engine timing issues can occur for several reasons, identifying the root cause early can help prevent further damage. This can also lower the risk of a more expensive BMW 1 Series engine repair.
Accurate testing by BMW experts is essential for understanding what’s happening within your engine and identifying the root cause of the issue.
At Protech Automotive, Newport, our team uses BMW technical data, manufacturer-grade equipment, and hands-on experience to investigate BMW exhaust camshaft problems, BMW VANOS failures, and broader BMW engine timing issues.
Here’s why drivers across Newport, Cardiff and the surrounding areas choose Protech Automotive for BMW engine repair:
- BMW experts working on your vehicle.
- Repairs backed by a 12-month parts and labour guarantee.
- A courtesy car is available to keep you moving while your BMW is with us.
Join the {{review-count}} other local drivers who’ve rated us {{average-rating}} stars on Google for accurate repairs with excellent value.
If your BMW is showing warning lights or timing-related concerns, call Protech Automotive, Newport on 01633 213713 to book your BMW check-up.
