BMW Exhaust Camshaft Problem
“It’s just not running right.”
That was the concern raised by Mr J, who operates a local used-car dealership.
One of his customers returned a recently purchased BMW 118i after experiencing a rough idle and repeated BMW engine warning light messages. Initial inspections at the used car dealership hadn’t revealed a clear cause.
With no apparent explanation, Mr J decided to bring the BMW to our expert technicians at CSN Autos, Wymondham, for a more in-depth review.
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 our BMW specialists identified, confirmed, and resolved the issue to restore smooth, reliable operation.
Our Initial Review of the BMW 118i Rough Idle Problem
When the BMW 118i arrived at CSN Autos, Wymondham, our technicians began the investigation by listening to Mr J and what he’d experienced with the vehicle. We then confirmed the symptoms through a structured review.
Mr J explained that the BMW had been displaying a BMW engine warning light, running unevenly at idle, and intermittently showing a drivetrain malfunction message. Checks carried out before the BMW arrived hadn’t identified a clear cause, so the focus was on understanding what the vehicle’s systems were reporting.
Using this background, we carried out an initial assessment that included:
- A visual inspection under the bonnet to check for disturbed components or signs of recent work.
- A full system scan using BMW manufacturer technical 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 cause for the symptoms, so our BMW experts 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 important things:
- The engine control unit had detected a fault affecting exhaust camshaft control and VANOS operation.
- The crankshaft and camshaft timing signals were no longer aligned.
- The BMW 118i rough idle and BMW engine warning light were linked, not separate issues.
While the fault codes supported the symptoms, further testing was required to uncover the cause of this BMW exhaust camshaft problem.
Identifying the BMW Exhaust Camshaft Problem Behind the Fault
With the earlier checks confirming active VANOS and synchronisation-related faults, our next step was to examine the BMW 118i engine timing system in greater detail. Problems in this area can arise from several sources, so a clear, evidence-led process was essential.
Using the official BMW technical data and guided testing procedures, our technicians followed a structured plan:
- Verify engine timing electronically using an oscilloscope to compare camshaft and crankshaft signals.
- Remove the rocker cover and associated components to allow physical inspection of the timing system.
- Review the VANOS components to determine whether the issue involved the control valves, pulley mechanism, or 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 prompting us to proceed to 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. This also allowed our team to carry out accurate physical timing checks.
Both the electronic analysis and the mechanical measurements reached the same conclusion.
The exhaust camshaft was not reaching the correct position in relation to the crankshaft.
Further checks focused on the systems responsible for adjusting and monitoring exhaust camshaft timing.
Two related faults were identified:
- A fault within the exhaust camshaft timing adjustment system that prevented correct camshaft positioning.
- An issue affecting how the exhaust camshaft position reference was being read.
As a result, the engine control system couldn’t reliably align 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 the drivetrain malfunction message.
With the cause of the BMW exhaust camshaft problem confirmed, the next step was to carry out the repair required to restore correct engine timing and normal operation.
Repairing the BMW Exhaust Camshaft Problem on a BMW 118i
Once the root cause of the BMW exhaust camshaft problem had been confirmed, our BMW experts contacted Mr J to explain the findings clearly, outlining what would be required to restore correct exhaust camshaft timing.
This ensured he understood what was causing the issue and what work would be needed to resolve it.
At CSN Autos, Wymondham, no work goes ahead until everything has been thoroughly discussed with you. That way, you remain in control of the decision-making process and are kept informed at every stage.
After reviewing the findings, Mr J approved the recommended repairs and gave us the green light to proceed with the repair work.
With authorisation in place, our experts sourced high-quality BMW replacement components and began repairing the vehicle in accordance with BMW’s repair guidance.
The repair was carried out in the following stages:
1. Removing the affected timing components
To access the faulty components, the necessary upper engine parts were removed in line with BMW repair guidance. This allowed the exhaust camshaft timing components to be removed safely and correctly, 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 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 ensure effective camshaft operation once the engine was reassembled.
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 as specified by BMW.
5. Reassembly of the Vehicle’s Components
Once timing had been confirmed, our technicians carried out full engine reassembly, following BMW procedures to ensure all components were refitted correctly and securely.
With the vehicle’s reassembly complete, the BMW 118i was ready to move into the final stage of the repair process – confirming the fault had been repaired.
Confirming the BMW Exhaust Camshaft Problem Was Resolved
Once the 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, our BMW specialists:
- Rechecked camshaft and crankshaft timing once the engine was fully reassembled.
- Ran system checks to ensure no related faults were present.
- Observed engine behaviour at idle and during a controlled road test.
These checks confirmed that correct exhaust camshaft timing had been restored, idle quality had returned to normal, and 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.
The vehicle left CSN Autos, Wymondham, running smoothly, with the BMW exhaust camshaft problem resolved and no further BMW engine warning light or engine timing issues present.
BMW Exhaust Camshaft Problem? Book Your Check-Up at CSN Autos
If your BMW 1 Series has a rough idle problem or is showing an engine warning light, it’s important to have it checked before it worsens.
BMW engine timing issues can occur in different ways. Identifying the cause early can help reduce the risk of further damage and avoid more costly BMW 1 Series engine repairs further down the line.
This is why accurate testing by experienced BMW technicians is essential.
At CSN Autos, Wymondham, 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 Wymondham, Norwich and the surrounding areas choose us for BMW engine repair:
- Award-winning BMW experts working on your vehicle.
- 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.
Join the {{review-count}} other drivers who’ve rated us {{average-rating}} stars on Google for expert repairs and outstanding value.
If your BMW is showing warning lights or timing-related symptoms, contact CSN Autos on 01953 425983 to book your BMW check-up. Our team will assess the issue and advise you on the next steps.
