BMW Exhaust Camshaft Problem
“It’s just not running right.”
That was the concern raised by Mr K, who manages a local used-car dealership.
A customer returned a BMW 118i that the used-car dealership had recently sold after it began experiencing a rough idle and repeated BMW engine warning light messages. However, the checks carried out by Mr K’s team hadn’t revealed an apparent cause of the issue.
With no obvious explanation, Mr K chose to bring the BMW to our BMW technicians at Fergies, Thatcham, for further investigation.
Although the cause wasn’t immediately obvious, the symptoms pointed to an underlying fault that required a structured diagnostic approach. That process led us to uncover a BMW exhaust camshaft problem affecting the engine’s operation.
Here’s how we uncovered the fault, identified its root cause, and carried out the repair that restored the BMW to peak working condition.
Our Initial Review of the BMW 118i Running Issue
When the BMW 118i arrived at Fergies, Thatcham, our BMW specialists began the investigation by listening to Mr K and what he’d experienced. We then confirmed the reported symptoms through a structured assessment.
Mr K explained that the BMW had been displaying a BMW engine warning light, running unevenly at idle, and intermittently showing a drivetrain malfunction message – it’s no wonder his customer had returned the vehicle.
As the checks his team carried out, the focus was on understanding what the vehicle’s systems were reporting.
Using this information, our BMW technicians carried out an initial assessment that included:
- A visual inspection under the bonnet to check for disturbed components or signs of recent work.
- A complete system scan using the official BMW manufacturer data to review stored and active fault codes.
- A controlled engine start to observe idle quality and overall engine behaviour.
The visual inspection didn’t reveal a clear explanation for the symptoms, so our team moved on to analysing the fault code information.
The scan identified two fault codes that were directly relevant 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 showed three key points:
- A fault had been detected affecting exhaust camshaft control and VANOS operation.
- The crankshaft and camshaft timing signals were no longer correctly synchronised.
- The BMW 118i rough idle and BMW engine warning light were part of the same issue.
While the fault codes supported the symptoms, our team knew further testing was required to uncover the cause of this BMW exhaust camshaft problem.
Tracing the BMW Exhaust Camshaft Problem to Its Source
With the initial checks confirming active VANOS and synchronisation-related faults, attention turned to a closer examination of the BMW 118i engine timing system. Issues in this area can stem from several sources, so a structured, evidence-led approach was required.
Using BMW technical data and guided testing procedures, our technicians followed a clear plan:
- Verify 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 issue involved the control valves, pulley mechanism, or the camshaft.
The oscilloscope readings marked a key point in the investigation. The signal patterns were consistent with incorrect exhaust camshaft timing, helping rule out a sensor-related issue and leading us to move on to a mechanical inspection.
To confirm this, the rocker cover and high-pressure fuel injectors were removed, providing full access to the camshaft and timing assembly. This also allowed precise physical timing checks to be carried out.
Both the electronic analysis and the mechanical measurements reached the same conclusion.
The BMW’s exhaust camshaft was not reaching the correct position in relation to the crankshaft.
Additional checks focused on the systems responsible for monitoring and adjusting exhaust camshaft timing.
Two related faults were identified:
- A fault within the vehicle’s exhaust camshaft timing adjustment system that prevented accurate camshaft positioning.
- An issue affecting how the BMW’s exhaust camshaft position reference was being read.
These issues prevented the engine control system from reliably aligning the requested camshaft position with its actual position. This caused incorrect valve timing, particularly at idle, triggering the BMW engine warning light, uneven running, and a worrying drivetrain malfunction message.
With the cause of the BMW exhaust camshaft problem identified, the next step was to carry out the repair needed to restore correct engine timing and normal operation.
Repairing the BMW Exhaust Camshaft Problem on the BMW 118i
Once the cause of the BMW exhaust camshaft problem had been found, our BMW technicians contacted Mr K to explain the findings clearly and outline what would be required to restore correct exhaust camshaft timing.
This ensured he had a clear understanding of what was causing the issue and what work would be needed to resolve it.
At Fergies, Thatcham, no work goes ahead until everything has been fully discussed and agreed. This means you remain in control of the decision-making process and are kept informed at every stage.
After reviewing the findings with our team, Mr K approved the recommended repairs and confirmed our experts could proceed with the fix.
With the green light to proceed, our specialists sourced high-quality BMW replacement components and began repairing the vehicle, following BMW procedures carefully throughout.
The repair was completed in the following stages:
1. Removing the affected BMW timing components
To access the faulty parts, the necessary upper engine components were removed in line with the official BMW repair guidance. This allowed our experts to safely and correctly remove the exhaust camshaft timing components, preparing the 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 reliable operation and correct positioning once reassembled.
3. Renewing supporting timing-control components
Related timing-control components, including parts of the VANOS system, were renewed during the repair to support consistent camshaft operation after reassembly.
4. Setting and confirming engine timing using BMW timing tools
With the new components installed, engine timing was set and verified to confirm the camshaft and crankshaft were correctly synchronised in line with BMW 118i’s specifications.
5. Reassembly of the BMW 118i Engine Components
Once the correct timing had been verified, our technicians fully reassembled the engine, following BMW procedures to ensure every component was refitted securely and in the correct position.
With reassembly complete, the BMW 118i was ready to move into the final stage of our repair process.
Final Checks: Confirming the BMW Exhaust Camshaft Repair
Once the BMW 118i rough idle repair was complete, our BMW experts carried out a series of checks to confirm the camshaft timing fault had been fully resolved and that the engine was operating as it should.
As part of this final confirmation stage, we:
- Rechecked camshaft and crankshaft timing once the engine was fully reassembled.
- Completed system checks to ensure no related faults were present.
- 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 quality had returned to normal, and that the drivetrain malfunction message was no longer present.
After completing the checks, we contacted Mr K to confirm the outcome. He was pleased with the work carried out and confident the BMW was running as expected.
The BMW left Fergies, Thatcham, 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 Fergies
If your BMW 1 Series has a rough idle problem or is showing an engine warning light, it’s essential to have it checked before it develops further.
BMW engine timing issues can arise in different ways. Identifying the cause early can help reduce the risk of further damage and may help you avoid more costly BMW 1 Series engine repair later on.
Accurate testing performed by a BMW expert is key to understanding what’s happening to your vehicle.
At Fergies, Thatcham, our team uses BMW technical data, manufacturer-level technology, and hands-on experience to investigate BMW exhaust camshaft problems, BMW VANOS failure, and wider BMW engine timing issues.
Here’s why drivers across Thatcham, Newbury, and Reading choose us for BMW engine repair:
- A courtesy car is available to keep you moving while your BMW is with us.
- Repairs backed by a 12-month parts and labour guarantee.
- Award-winning BMW experts working on your vehicle.
Join the {{review-count}} other drivers who’ve rated us {{average-rating}} stars on Google for excellent value and expert repairs.
If your BMW shows signs of a timing issue or an engine warning light, call our team at Fergies, Thatcham on 01635 778002 to book your BMW check-up.
