BMW exhaust camshaft problem solved for BMW 118i

BMW Exhaust Camshaft Problem And How It Was Solved

“It’s clearly not behaving as it should.”

That was what Mr J, who manages a local used-car dealership, said when he brought his vehicle to us.

One of his customers had brought back a BMW 118i shortly after purchase, reporting an uneven idle and an illuminated engine warning light. His team had performed a few checks already, but hadn’t identified the root of the problem.

Without an obvious cause, he called our BMW experts at Roade Main Garage, Northampton, to investigate further.

While the issue wasn’t immediately clear to our team, the symptoms suggested an underlying fault that needed a structured diagnostic approach. That process ultimately revealed a BMW exhaust camshaft problem affecting engine operation.

Throughout this blog, you’ll reveal how the issue was identified, what was causing it, and how we solved the BMW 118i rough idle problem.

How We Began Investigating the BMW 118i Rough Idle

When Mr J brought his BMW 118i to Roade Main Garage, Northampton, our technicians began by listening carefully to his account of the problem before confirming the reported symptoms through structured checks.

Mr J explained that the vehicle had been showing an engine warning light, running unevenly at idle, and intermittently displaying a drivetrain malfunction message.

Checks carried out at his used-car dealership hadn’t identified the cause, leaving us to interpret what the engine management system was reporting.

Based on this information, our BMW specialists carried out an initial evaluation that involved:

Inspecting the engine bay for disturbed components or signs of recent work.
Completing a full system scan using BMW manufacturer data to review stored and active fault codes.
Starting the engine in a controlled environment to assess idle stability and behaviour.

As the visual inspection didn’t reveal a clear cause, attention turned to the fault code information.

The system scan identified two fault codes linked directly to the symptoms:

160021 – Crankshaft sensor loss of synchronisation
130304 – VANOS exhaust camshaft jammed

(VANOS is BMW’s variable valve timing system, designed to adjust camshaft position during engine operation).

Together, these fault codes highlighted three key points:

The crankshaft and camshaft were no longer aligned correctly.
The rough idle issue and the BMW engine warning light were symptoms of the same underlying issue.
A fault had been detected within the exhaust camshaft control side of the VANOS system

While our team’s findings confirmed which systems were affected, they didn’t explain the root cause. Our team recognised that a deeper investigation was needed to identify the source of this BMW exhaust camshaft issue.

Tracing the Root Cause of the BMW Exhaust Camshaft Problem

Our team’s initial findings pointed towards VANOS and synchronisation issues, so the next step was a deeper inspection of the BMW 118i engine timing system. Given the number of potential causes, a careful and methodical approach was essential.

Using BMW technical data and guided testing procedures, our technicians followed a structured plan:

Checking engine timing electronically by comparing camshaft and crankshaft signals.
Removing the rocker cover and associated components to inspect the timing system physically.
Assessing the VANOS system to establish whether the fault lay with the valves, pulley, or camshaft.

The electronic timing results marked an important turning point in our expert’s investigation. The signal patterns suggested incorrect exhaust camshaft timing and ruled out a sensor-only issue. This prompted our team to move on to a mechanical inspection.

To confirm the findings, the rocker cover and high-pressure fuel injectors were removed, giving clear access to the camshaft and timing assembly and enabling accurate physical timing checks.

Both electronic and mechanical checks pointed to the same conclusion…

The exhaust camshaft wasn’t reaching the correct position relative to the crankshaft.

Additional checks then focused on the systems responsible for adjusting and monitoring exhaust camshaft timing.

Two related faults were identified:

A failure within the exhaust camshaft timing adjustment system was preventing accurate positioning.
The exhaust camshaft position reference wasn’t being interpreted correctly.

Because of this, the vehicle’s engine control unit couldn’t reliably match the commanded camshaft position with the actual position. This resulted in incorrect valve timing at idle, triggering the rough running, engine warning light, and drivetrain malfunction message.

With the cause of the BMW 118i rough idle confirmed, our team’s attention turned to carrying out the repairs needed to restore correct engine operation.

How Was the BMW Exhaust Camshaft Problem Fixed on This BMW 118i?

After confirming the cause of the BMW rough idle, our experts spoke with Mr J and explained the findings in clear terms, detailing what was affecting camshaft timing and what would be required to correct it.

This gave him a full understanding of the issue and the steps needed to return the engine to correct operation.

At Roade Main Garage, Northampton, repairs only proceed once everything has been clearly discussed and approved. This ensures you remain informed and in control throughout the process.

Once Mr J was happy with the proposed repair, he authorised the work and asked us to continue.

With the repair approved, our technicians sourced suitable BMW replacement parts and began the repair, following BMW procedures at every stage.

The repair process included:

1. Removing the affected timing components

Upper engine components were removed in line with BMW guidelines to safely access and remove the exhaust camshaft timing components.

2. Installing the replacement exhaust camshaft and timing components

The new exhaust camshaft and associated timing components were installed following BMW manufacturer procedures to ensure correct alignment.

3. Renewing related timing-control components

As part of the BMW rough idle repair, the related timing-control components, including elements of the VANOS system, were renewed. This helped support accurate camshaft operation once the engine was fully reassembled.

4. Setting and verifying engine timing using BMW timing tools

Engine timing was set and checked to confirm the camshaft and crankshaft were synchronised correctly.

5. Reassembly

Once timing had been confirmed, the engine was fully reassembled following BMW procedures, ensuring all components were refitted correctly and securely.

After the reassembly was complete, the BMW 118i was ready for the final confirmation checks.

Verifying the BMW Exhaust Camshaft Problem Had Been Fixed

After the repair was completed, our technicians performed a series of checks to ensure the camshaft timing issue had been fully corrected and the engine was functioning normally.

Confirming the repair was successful involved:

Rechecking camshaft and crankshaft timing once reassembled.
Carrying out system checks to confirm all related faults had cleared.
Assessing engine behaviour at idle and during a controlled road test.

The results showed that camshaft timing had been restored, the BMW 118i was no longer suffering from rough idle, and the drivetrain malfunction message did not return.

Our BMW experts then called Mr J with the results. He was happy that the vehicle’s rough idle problem had been solved and felt reassured that the BMW was now operating correctly.

He left Roade Main Garage, Northampton, with the vehicle running smoothly, with no BMW engine warning light and the engine timing issue resolved.

BMW Exhaust Camshaft Problems? Arrange a BMW Check-Up at Roade Main Garage

If your BMW 118i is rough idling or displaying an engine warning light, having the issue assessed early can help prevent further complications.

BMW engine timing issues don’t always present clearly, and understanding the cause sooner rather than later can reduce the risk of more extensive BMW 1 Series engine repair. A professional BMW check-up helps identify what’s happening beneath the surface.

At Roade Main Garage, Northampton, our technicians use BMW technical data and manufacturer-grade tools to investigate issues such as BMW exhaust camshaft problems, BMW VANOS failure, and engine timing irregularities.