BMW Exhaust Camshaft Problem
“Something isn’t adding up here.”
That was the concern raised by Mr O, who operates a local used-car dealership.
A recently sold BMW 118i was brought back after the customer reported a rough idle and repeated BMW engine warning light messages. Despite checks by the used-car dealership, the cause of the issue remained unclear.
Wanting to get to the bottom of the issue, Mr O brought the BMW 118i to our team at P. Breading Motor Services, Southend-on-Sea, for a more detailed assessment.
Although the cause wasn’t immediately apparent, the symptoms indicated a fault that required a structured diagnostic process. This approach allowed us to identify a BMW exhaust camshaft problem affecting overall engine timing.
Throughout this blog, you’ll learn how the issue was identified, the root cause confirmed, and how reliable performance was restored.
BMW 118i Rough Idle: The Initial Assessment
When the BMW arrived at P. Breading Motor Services, Southend-on-Sea, our technicians began by listening to Mr O’s account of the issue, then we confirmed the symptoms through a structured assessment.
Mr O explained that the BMW had been displaying a BMW engine warning light, running unevenly at idle, and intermittently showing a drivetrain malfunction message. Earlier checks carried out by the used-car dealership hadn’t uncovered the cause, so attention shifted to what the vehicle’s systems were reporting.
Using this background, our initial assessment included:
- A visual check under the bonnet to identify any disturbed components or evidence of previous work.
- A complete system scan using BMW manufacturer data to review stored or active fault codes.
- A controlled engine start to assess idle quality and overall engine behaviour.
The visual inspection our experts performed didn’t point to a clear explanation, so the system fault code data was reviewed in more detail.
The scan identified two fault codes linked directly to the reported concerns:
- 160021 – Crankshaft sensor loss of synchronisation
- 130304 – VANOS exhaust cam jammed
(VANOS is BMW’s trademarked name for its variable valve timing system, which adjusts camshaft positioning to support efficient engine operation.)
Together, these findings showed three important things:
- The BMW 118i rough idle and BMW engine warning light were related, not separate issues.
- The engine control unit had detected a fault affecting exhaust camshaft control and VANOS operation.
- Crankshaft and camshaft timing were no longer correctly aligned.
While the fault codes reflected the symptoms, they didn’t reveal the root cause. Additional testing was required to fully understand this BMW exhaust camshaft problem.
Identifying the Source of the BMW Exhaust Camshaft Problem
After the initial checks confirmed VANOS-related and synchronisation faults, the next step was a closer examination of the BMW 118i engine timing system. Several components influence timing accuracy, so a structured diagnostic approach was essential.
Using BMW technical data and guided testing routines, our technicians followed a defined process:
- Verify engine timing electronically using an oscilloscope to compare camshaft and crankshaft signals.
- Remove the rocker cover and associated components to inspect the timing system directly.
- Review the VANOS components to determine whether the fault involved the control valves, pulley mechanism, or camshaft.
The oscilloscope results marked a key stage in our expert’s investigation. The signal patterns showed incorrect exhaust camshaft timing, ruling out a sensor-related issue and directing the investigation toward mechanical inspection.
To confirm this, the rocker cover and high-pressure fuel injectors were removed, giving full access to the camshaft and timing assembly. Doing so allowed precise physical timing checks to be carried out.
Both electronic testing and mechanical measurement led to the same conclusion…
The exhaust camshaft was unable to reach its correct position relative to the crankshaft.
Further checks focused on the systems responsible for adjusting and monitoring exhaust camshaft timing.
Two related faults were identified:
- A problem within the exhaust camshaft timing adjustment system that prevented accurate camshaft positioning.
- An issue affecting how the exhaust camshaft position reference was being read.
Because of this, the BMW’s engine control system couldn’t reliably align the requested camshaft position with its actual position, resulting in incorrect valve timing.
This was particularly noticeable during idling, triggering the BMW engine warning light, uneven running, and the drivetrain malfunction message.
With the BMW exhaust camshaft problem confirmed, the next step was to carry out the required repair.
Carrying Out Repairs for the BMW Exhaust Camshaft Problem
Once the BMW exhaust camshaft problem had been identified, our BMW experts called Mr O to discuss our findings and outline the repair work required to restore correct engine timing.
This ensured he fully understood the cause of the issue and the steps needed to resolve it.
At P. Breading Motor Services, Southend-on-Sea, no work proceeds until everything has been discussed and agreed, keeping you in the know throughout the process. You’re always in total control with us.
After authorisation was given, our team sourced high-quality BMW replacement components and began the repair, following BMW manufacturer procedures at every stage.
The BMW 118i repair process included:
1. Removing the affected timing components
To reach the affected components, the required upper engine parts were removed in line with BMW repair guidance. This provided safe access to the exhaust camshaft timing components and prepared the engine for repair.
2. Installing the replacement exhaust camshaft and timing components
The replacement exhaust camshaft and associated timing parts were installed in accordance with BMW specifications to ensure accurate positioning.
3. Renewing supporting timing-control components
As part of the repair process, the related timing-control components, including components of the BMW VANOS system, were renewed to ensure reliable camshaft operation.
4. Setting and confirming engine timing using BMW timing tools
Engine timing was set and verified to confirm correct synchronisation between the camshaft and crankshaft.
5. Completing the BMW engine reassembly
Once timing had been confirmed, the engine was carefully reassembled, ensuring all components were refitted securely and correctly.
With engine reassembly complete, the BMW 118i was ready to progress to the final stage of the fix, confirming the repair.
Verifying Correct Operation After BMW Camshaft Repair
Once the repair was complete, our BMW experts carried out a series of confirmation checks to ensure the exhaust camshaft timing fault had been fully resolved and the engine was operating as expected.
This final stage included:
- Rechecking camshaft and crankshaft timing after reassembly.
- Completing system checks to confirm no related faults were present.
- Observing engine behaviour at idle and during a controlled road test.
These checks confirmed that the correct camshaft timing had been restored, that idle stability had returned, and the drivetrain malfunction message no longer appeared.
Once our team had confirmed the repair was successful, the vehicle was ready to be handed back to Mr O.
Our BMW experts called Mr O to let him know the BMW was back in top working condition and was ready for collection. He was pleased with the quality of the repair, the clear explanations throughout the process, and the value he’d received.
He left our garage with the BMW 118i 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 P. Breading Motor Services
If your BMW 118i has a rough idle or an engine warning light, it’s best to have the issue checked before it worsens.
BMW engine timing issues can develop for many different reasons, and early identification can help limit further damage and reduce the risk of a more costly BMW 1 Series engine repair.
Accurate testing by BMW experts plays a key role in understanding what’s happening within your engine and pinpointing the underlying cause.
At P. Breading Motor Services, Southend-on-Sea, our team uses BMW technical data, manufacturer-level technology, and practical experience to investigate BMW exhaust camshaft problems, BMW VANOS failure, and wider BMW engine timing issues.
Here’s why drivers across Southend and Great Wakering choose P. Breading Motor Services for BMW engine repair:
- BMW-experienced technicians working on your vehicle.
- Repairs backed by a 12-month parts and labour guarantee.
- A courtesy car is available to keep you mobile while your vehicle is being repaired.
Join the {{review-count}} other drivers who’ve rated us {{average-rating}} stars on Google for accurate repairs and excellent value.
If your BMW is showing timing-related symptoms or warning lights, call P. Breading Motor Services on 01702 535710 to book your BMW check-up.
